JP4271060B2 - Niobium oxide powder - Google Patents
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- 229910000484 niobium oxide Inorganic materials 0.000 title claims description 84
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 title claims description 84
- 239000000843 powder Substances 0.000 title claims description 77
- 239000011737 fluorine Substances 0.000 claims description 23
- 229910052731 fluorine Inorganic materials 0.000 claims description 23
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 22
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 22
- 229910052750 molybdenum Inorganic materials 0.000 claims description 22
- 239000011733 molybdenum Substances 0.000 claims description 22
- 238000002441 X-ray diffraction Methods 0.000 claims description 12
- 239000007788 liquid Substances 0.000 description 174
- 239000010955 niobium Substances 0.000 description 123
- 229910052758 niobium Inorganic materials 0.000 description 121
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 121
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 100
- 238000000605 extraction Methods 0.000 description 87
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 68
- 239000000243 solution Substances 0.000 description 56
- 239000003960 organic solvent Substances 0.000 description 54
- 229910052715 tantalum Inorganic materials 0.000 description 53
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 53
- 238000004140 cleaning Methods 0.000 description 32
- 238000002156 mixing Methods 0.000 description 29
- 238000005406 washing Methods 0.000 description 29
- 239000002244 precipitate Substances 0.000 description 27
- 238000000638 solvent extraction Methods 0.000 description 25
- 239000007864 aqueous solution Substances 0.000 description 23
- 238000000034 method Methods 0.000 description 21
- 238000002360 preparation method Methods 0.000 description 19
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 18
- 238000004519 manufacturing process Methods 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 14
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 13
- 239000012535 impurity Substances 0.000 description 13
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 12
- 239000013078 crystal Substances 0.000 description 12
- 239000000203 mixture Substances 0.000 description 12
- 239000012071 phase Substances 0.000 description 12
- 238000005259 measurement Methods 0.000 description 11
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 10
- 239000002253 acid Substances 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 8
- 235000011114 ammonium hydroxide Nutrition 0.000 description 8
- 229910052500 inorganic mineral Inorganic materials 0.000 description 8
- 239000011707 mineral Substances 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 239000005304 optical glass Substances 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 6
- 239000000919 ceramic Substances 0.000 description 6
- 239000011521 glass Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 229910017604 nitric acid Inorganic materials 0.000 description 6
- 239000010409 thin film Substances 0.000 description 6
- 229910021529 ammonia Inorganic materials 0.000 description 5
- 239000008346 aqueous phase Substances 0.000 description 5
- 238000001914 filtration Methods 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 4
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 4
- 239000001099 ammonium carbonate Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- QPJSUIGXIBEQAC-UHFFFAOYSA-N n-(2,4-dichloro-5-propan-2-yloxyphenyl)acetamide Chemical compound CC(C)OC1=CC(NC(C)=O)=C(Cl)C=C1Cl QPJSUIGXIBEQAC-UHFFFAOYSA-N 0.000 description 4
- AOLPZAHRYHXPLR-UHFFFAOYSA-I pentafluoroniobium Chemical compound F[Nb](F)(F)(F)F AOLPZAHRYHXPLR-UHFFFAOYSA-I 0.000 description 4
- 238000005191 phase separation Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- STCOOQWBFONSKY-UHFFFAOYSA-N tributyl phosphate Chemical compound CCCCOP(=O)(OCCCC)OCCCC STCOOQWBFONSKY-UHFFFAOYSA-N 0.000 description 4
- 229910016523 CuKa Inorganic materials 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 3
- -1 lithium niobate (LN) Chemical compound 0.000 description 3
- 230000001376 precipitating effect Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 2
- 235000012501 ammonium carbonate Nutrition 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000005477 sputtering target Methods 0.000 description 2
- 238000004448 titration Methods 0.000 description 2
- 238000002834 transmittance Methods 0.000 description 2
- 229910021642 ultra pure water Inorganic materials 0.000 description 2
- 239000012498 ultrapure water Substances 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 1
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- MMDJDBSEMBIJBB-UHFFFAOYSA-N [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] Chemical compound [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] MMDJDBSEMBIJBB-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- LDDQLRUQCUTJBB-UHFFFAOYSA-O azanium;hydrofluoride Chemical compound [NH4+].F LDDQLRUQCUTJBB-UHFFFAOYSA-O 0.000 description 1
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000006193 liquid solution Substances 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 229910001936 tantalum oxide Inorganic materials 0.000 description 1
- 238000009283 thermal hydrolysis Methods 0.000 description 1
- 238000003828 vacuum filtration Methods 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
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Description
本発明は、酸化ニオブ粉末に関する。 The present invention relates to niobium oxide powder.
酸化ニオブは、ニオブ酸リチウム（ＬＮ）等のニオブを含有する単結晶、スパッタリングターゲットまたは蒸着用ペレット等の薄膜形成材料、光学製品やファインセラミックなどの原料等として広く用いられている。 Niobium oxide is widely used as a single crystal containing niobium such as lithium niobate (LN), a thin film forming material such as a sputtering target or a pellet for vapor deposition, a raw material for optical products, fine ceramics, and the like.
このようにして用いられる酸化ニオブ粉末としては、流動性や均一混合性がよいことが求められており、また、一部の用途を除けば、低温での焼結しやすさや、酸化ニオブ以外の粉末との低温での反応のしやすさが求められている。このような要求を満たすために、例えばＢＥＴ法比表面積が２ｍ２／ｇ未満で、かつタップ法見掛け密度が１．８ｇ／ｃｃ以上である酸化ニオブ粉末、あるいはＢＥＴ法比表面積が２ｍ２／ｇ以上で、かつタップ法見掛け密度が１．８ｇ／ｃｃ未満である酸化ニオブ粉末が検討されている（特許文献１参照）。
しかしながら、ＢＥＴ法比表面積とタップ法比表面積を上記範囲内にしても、流動性および均一混合性の少なくとも一方は満足すべきものではなかった。 However, even when the BET method specific surface area and the tap method specific surface area are within the above ranges, at least one of fluidity and uniform mixing property is not satisfactory.
このような問題点に鑑みてなされた本発明は、流動性および均一混合性に優れた酸化ニオブ粉末を得ることを課題とする。 This invention made | formed in view of such a problem makes it a subject to obtain the niobium oxide powder excellent in fluidity | liquidity and uniform mixing property.
このような課題を解決するために、酸化ニオブ粉末について検討を重ねた結果、次のような酸化ニオブ粉末が流動性および均一混合性に優れていることを見出し、本発明に想到するに至った。すなわち、本発明は、ＣｕＫα１線を用いたＸ線回折分析における２θ（回折角）＝２０°〜３０°の範囲の最大ピークは半値幅が０．０８°〜０．８°である酸化ニオブ粉末である。 As a result of repeated studies on niobium oxide powder in order to solve such problems, the following niobium oxide powder was found to be excellent in fluidity and uniform mixing properties, and led to the present invention. . That is, according to the present invention, the maximum peak in the range of 2θ (diffraction angle) = 20 ° to 30 ° in the X-ray diffraction analysis using CuKα 1 line is niobium oxide having a half width of 0.08 ° to 0.8 °. It is a powder.
本発明に係る酸化ニオブ粉末は、ガラス（特に光学ガラス）用、セラミック用、薄膜形成材料（スパッタリングターゲットまたは蒸着用ペレット等）用さらにはニオブ酸リチウム（ＬＮ）用として好適である。前記半値幅が上限値を超える酸化ニオブは、流動性や均一混合性に劣っているという点でセラミック用、薄膜形成材料用あるいはニオブ酸リチウム（ＬＮ）用等の用途として適当でなく、泡発生の原因になりやすく且つ発生した泡が消えにくいという点でガラス（特に光学ガラス）用の用途としても適当でないからである。他方、前記半値幅が下限値未満の酸化ニオブは、均一焼結性に劣っているという点でセラミック用、薄膜形成材料用あるいはニオブ酸リチウム（ＬＮ）用としては適当でなく、また溶解しにくいという点でガラス（特に光学ガラス）用の用途としても適当でないからである。このようなことから、流動性、均一混合性および難泡発生性に優れると共に、均一焼結性やガラス溶解性に優れるものがより好ましいという点では、酸化ニオブ粉末としては、前記半値幅（２θ）が０．１°〜０．５°であるものがより好ましく、０．１５°〜０．４°であるものがさらに好ましい。 The niobium oxide powder according to the present invention is suitable for glass (particularly optical glass), for ceramics, for thin film forming materials (sputtering targets or vapor deposition pellets), and for lithium niobate (LN). Niobium oxide whose half width exceeds the upper limit is not suitable for ceramics, thin film forming materials, or lithium niobate (LN) because it is inferior in fluidity and uniform mixing properties, and generates bubbles. This is because it is not suitable as an application for glass (particularly optical glass) in that the generated bubbles are difficult to disappear and the generated bubbles are difficult to disappear. On the other hand, niobium oxide having a half width less than the lower limit is not suitable for ceramics, thin film forming materials or lithium niobate (LN) in that it has poor uniform sinterability and is difficult to dissolve. This is because it is not suitable as a use for glass (particularly optical glass). For this reason, the niobium oxide powder is more preferable in terms of the half-width (2θ) in that it is excellent in fluidity, uniform mixing properties, and difficult-to-foam generation, and more preferable in terms of uniform sinterability and glass solubility. ) Is more preferably 0.1 ° to 0.5 °, and more preferably 0.15 ° to 0.4 °.
そして、本発明に係る酸化ニオブ粉末では、測定の結果、Ｘ線回折分析における２θ（回折角）＝２０°〜３０°の最大ピークは、２θ＝２２．６°±０．５°および／または２θ＝２８．４°±０．４°の位置に出現するか、２θ＝２３．２°〜２６．２°の位置に出現する。最大ピークが２θ＝２２．６°±０．５°および／または２θ＝２８．４°±０．４°の位置に出現する場合にあっては、ピークが両方の位置に出現する場合が多く、２θ＝２２．６°±０．５°の位置に出現するピークの方が最大ピークになる場合が多い。また、最大ピークが２θ＝２３．２°〜２６．２°の位置に出現する場合の、主なピークの出現位置は、２θ＝２３．７°±０．５°、２θ＝２４．７°±０．４°および２θ＝２５．７°±０．５°である。各位置に出現するピーク数は１つずつの場合が多いがいずれかの位置または全ての位置に２つ以上出現する場合もある。また、いずれの位置に出現するピークとも最大ピークになる可能性があるが、２θ＝２３．７°±０．５°位置に出現するピークが最大ピークになる場合が多い。そして、検討の結果、上記のいずれかの範囲に最大ピークが出現する酸化ニオブ粉末であって、最大ピークの半値幅が上記好適範囲内であるものは、上記用途に好適な酸化ニオブ粉末であることが解った。 In the niobium oxide powder according to the present invention, as a result of measurement, the maximum peak of 2θ (diffraction angle) = 20 ° to 30 ° in X-ray diffraction analysis is 2θ = 22.6 ° ± 0.5 ° and / or It appears at a position of 2θ = 28.4 ° ± 0.4 °, or appears at a position of 2θ = 23.2 ° to 26.2 °. When the maximum peak appears at a position of 2θ = 22.6 ° ± 0.5 ° and / or 2θ = 28.4 ° ± 0.4 °, the peak often appears at both positions. The peak that appears at a position of 2θ = 22.6 ° ± 0.5 ° is often the maximum peak. Moreover, when the maximum peak appears at a position of 2θ = 23.2 ° to 26.2 °, the appearance position of the main peak is 2θ = 23.7 ° ± 0.5 °, 2θ = 24.7 °. ± 0.4 ° and 2θ = 25.7 ° ± 0.5 °. The number of peaks that appear at each position is often one at a time, but two or more peaks may appear at any position or at all positions. In addition, there is a possibility that the peak appearing at any position may be the maximum peak, but the peak appearing at the position 2θ = 23.7 ° ± 0.5 ° is often the maximum peak. As a result of the study, the niobium oxide powder in which the maximum peak appears in any one of the above ranges, and the half peak width of the maximum peak within the above preferable range is the niobium oxide powder suitable for the above application. I understood that.
また、本発明に係る酸化ニオブ粉末としては、Ｘ線回折分析において２θ＝２２．６°±０．５°の位置に出現するピークおよび２θ＝２８．４°±０．４°の位置に出現するピークのうちの最大ピークのピーク値Ｐと、２θ＝２３．２°〜２６．２°の範囲の最大ピークのピーク値Ｑとのピーク強度比（Ｑ／Ｐ）が、下限値としては、０．５以下であるものが好ましい。また、上限値としては、２以上であるものが好ましい。ピーク強度比が０．５を超え、２未満の範囲である酸化ニオブ粉末は、流動性が実用範囲ではあるが、わずかに悪いからである。 Further, the niobium oxide powder according to the present invention has a peak appearing at a position of 2θ = 22.6 ° ± 0.5 ° and a position of 2θ = 28.4 ° ± 0.4 ° in X-ray diffraction analysis. The peak intensity ratio (Q / P) between the peak value P of the maximum peak among the peaks to be peaked and the peak value Q of the maximum peak in the range of 2θ = 23.2 ° to 26.2 °, What is 0.5 or less is preferable. Moreover, as an upper limit, what is 2 or more is preferable. This is because the niobium oxide powder having a peak intensity ratio of more than 0.5 and less than 2 has a fluidity in a practical range but is slightly worse.
なお、ＣｕＫα１線を用いたＸ線回折分析には、試料にＣｕＫα１線を照射して回折Ｘ線を得るという分析方法のほか、より一般的な方法すなわち、試料にＣｕＫα線を照射して得られる回折Ｘ線をＣｕＫα１線によるものとＣｕＫα２線によるものとに分離して、ＣｕＫα１線に対応する回折Ｘ線を得るという分析方法も含まれる。 In addition, in the X-ray diffraction analysis using the CuKα 1 line, in addition to the analysis method of obtaining a diffracted X-ray by irradiating the sample with CuKα 1 line, a more general method, ie, irradiating the sample with CuKα line the diffracted X-rays obtained by separated into the by the CuKa 2 line by CuKa 1 line, includes a method analyzing of obtaining diffracted X-rays corresponding to CuKa 1 line.
そして、ここでいうピーク半値幅とは、ＪＩＳ Ｋ ０１３１−1996「Ｘ線回折分析通則」の図６半値幅（β１／２）のことである。半値幅の単位は、同ＪＩＳの「１２．結晶子の大きさと不均一ひずみの測定」においては「ｒａｄ」であるが、ここでは「°」で表示した。 The peak half-value width here refers to the half-value width (β 1/2 ) in FIG. 6 of JIS K 0131-1996 “General Rules for X-ray Diffraction Analysis”. The unit of the full width at half maximum is “rad” in “12. Measurement of crystallite size and non-uniform strain” of the same JIS, but here it is indicated by “°”.
本発明に係る酸化ニオブ粉末は、例えば、概略的には次のようにして製造される。まず、ニオブを含有する原料（例えば、鉱石、合金あるいはスクラップ等）を用意した後、原料に対し、必要に応じて、粉砕、アルカリ水溶液による疎解さらにはフッ化水素酸（ＨＦ）以外の鉱酸による洗浄といった処理を行う。次に、少なくともフッ化水素酸を含有する酸で原料を溶解して溶解液を得る。そして、得られた溶解液に、必要に応じて、フッ化水素酸、フッ化水素酸以外の鉱酸（例えば硫酸）および水を加えて、所定の状態に調製された液調整液を得る。液調整液を得ると、これに溶媒抽出を施してニオブ精製液（フッ化ニオブ溶液）を得る。次に、得られたフッ化ニオブ溶液とアンモニア水などの沈澱剤とを混合して沈澱物を得る。そして、得られた沈澱物を洗浄し、ろ過等によって液体部分から分離し、分離された沈澱物を焼成すると酸化ニオブが得られる。 The niobium oxide powder according to the present invention is produced, for example, schematically as follows. First, after preparing a raw material containing niobium (for example, ore, alloy or scrap), the raw material is pulverized, disaggregated with an aqueous alkaline solution, or mineral other than hydrofluoric acid (HF) as necessary. Processing such as washing with acid is performed. Next, the raw material is dissolved with an acid containing at least hydrofluoric acid to obtain a solution. Then, if necessary, hydrofluoric acid, mineral acid other than hydrofluoric acid (for example, sulfuric acid) and water are added to the obtained solution to obtain a liquid adjusting liquid prepared in a predetermined state. When a liquid adjustment liquid is obtained, solvent extraction is performed on the liquid adjustment liquid to obtain a niobium purified liquid (niobium fluoride solution). Next, the obtained niobium fluoride solution and a precipitant such as aqueous ammonia are mixed to obtain a precipitate. Then, the obtained precipitate is washed, separated from the liquid portion by filtration or the like, and the separated precipitate is baked to obtain niobium oxide.
このような酸化ニオブ粉末の製造方法中、ニオブ精製液を得るための溶媒抽出は、液調整液（タンタル抽出用液調整液）から有機溶媒にタンタルを抽出するタンタル抽出工程と、ニオブを含んでいるがタンタルが抽出された残液（水溶液相）をニオブ抽出用液調整液に調製する調製工程と、ニオブ抽出用液調整液から有機溶媒にニオブを抽出するニオブ抽出工程と、精製されたニオブ含有有機溶媒を得る洗浄工程と、ニオブを水溶液相に抽出する逆抽出工程と、を有するものである。なお、調製工程は、タンタル抽出工程で得られた残液がニオブ抽出用液調整液として適当でない場合に必要に応じて行われる工程である。溶媒抽出で用いる有機溶媒としては、種々のものを挙げることができるが、４−メチル−２−ペンタノン（メチルイソブチルケトンやＭＩＢＫ（略称）と称されることがある）またはトリブチルホスフェート（略称はＴＢＰ）が好適である。４−メチル−２−ペンタノンは希釈せずに使用されるが、トリブチルホスフェートは、石油系炭化水素等の希釈剤で希釈して使用されることが多い。 In such a method for producing niobium oxide powder, solvent extraction for obtaining a niobium purified solution includes a tantalum extraction step of extracting tantalum from a liquid adjustment liquid (tantalum extraction liquid adjustment liquid) into an organic solvent, and niobium. A tantalum-extracted residual solution (aqueous phase) is prepared as a liquid preparation for niobium extraction, a niobium extraction process for extracting niobium from the liquid adjustment liquid for niobium extraction into an organic solvent, and purified niobium A washing step for obtaining a contained organic solvent, and a back extraction step for extracting niobium into an aqueous phase. In addition, a preparation process is a process performed as needed, when the residual liquid obtained at the tantalum extraction process is not suitable as a liquid adjustment liquid for niobium extraction. Examples of the organic solvent used in the solvent extraction include 4-methyl-2-pentanone (sometimes called methyl isobutyl ketone or MIBK (abbreviation)) or tributyl phosphate (abbreviation TBP). ) Is preferred. 4-Methyl-2-pentanone is used without being diluted, but tributyl phosphate is often used after being diluted with a diluent such as petroleum hydrocarbon.
溶媒抽出では、まずタンタル抽出工程において有機溶媒とタンタル抽出用液調整液を接触させて、有機溶媒にタンタルを抽出する。すると、タンタルのほぼ全量とタンタル以外の物質の一部が有機溶媒に抽出され、タンタル以外の物質の大部分が残液（水溶液相）に残る。つづく液調製工程では、得られた残液に、必要に応じて、フッ化水素酸、フッ化水素酸以外の鉱酸（例えば硫酸）あるいは水を加えてニオブ抽出用液調整液を調製する。そして、ニオブ抽出工程において、有機溶媒とニオブ抽出用液調整液とを接触させて、有機溶媒にニオブを抽出する。すると、ニオブのほぼ全量とニオブ以外の不純物の一部が有機溶媒に抽出され、ニオブ以外の不純物の大部分が水溶液相に残る。その後の洗浄工程では、抽出されたニオブおよび不純物を含む有機溶媒と洗浄液とを接触させて、不純物のほぼ全量とニオブの一部とを水溶液相に抽出させる。すると、ニオブの大部分が有機溶媒中に残り、精製されたニオブ含有有機溶媒が得られる。さらに、その後に行われる逆抽出工程では、得られたニオブ含有有機溶媒と逆抽出用に用意した水溶液とを接触させて、ニオブを水溶液相に逆抽出する。これにより、有機溶媒中のニオブの大部分が水溶液相に抽出され、ニオブ精製液が得られる。 In the solvent extraction, first, in the tantalum extraction step, the organic solvent and the tantalum extraction liquid adjusting solution are brought into contact with each other to extract tantalum into the organic solvent. Then, almost the entire amount of tantalum and a part of the substance other than tantalum are extracted into the organic solvent, and most of the substance other than tantalum remains in the residual liquid (aqueous solution phase). In the subsequent liquid preparation step, a liquid adjustment liquid for niobium extraction is prepared by adding hydrofluoric acid, mineral acid other than hydrofluoric acid (for example, sulfuric acid) or water to the obtained residual liquid as necessary. Then, in the niobium extraction step, the organic solvent is brought into contact with the liquid adjustment solution for niobium extraction to extract niobium into the organic solvent. Then, almost the entire amount of niobium and a part of impurities other than niobium are extracted into the organic solvent, and most of the impurities other than niobium remain in the aqueous solution phase. In the subsequent washing step, the extracted organic solvent containing niobium and impurities and the washing liquid are brought into contact with each other to extract almost the entire amount of impurities and a part of niobium into the aqueous phase. Then, most of the niobium remains in the organic solvent, and a purified niobium-containing organic solvent is obtained. Further, in the subsequent back extraction step, the obtained niobium-containing organic solvent is brought into contact with an aqueous solution prepared for back extraction, so that niobium is back extracted into an aqueous phase. Thereby, most of the niobium in the organic solvent is extracted into the aqueous solution phase, and a niobium purified solution is obtained.
溶媒抽出のタンタル抽出工程について、より具体的に説明すると、本工程に供用されるタンタル抽出用液調整液としては、過剰のフッ化水素酸含有量が０．１ｍｏｌ／Ｌ〜２．０ｍｏｌ／Ｌが好ましい。下限値未満ではタンタルの有機溶媒への抽出が不十分になりやすく、上限値を超えるとニオブの有機溶媒への抽出割合が増えてしまうからである。これらの点を考慮すると、上記過剰のフッ化水素酸含有量は０．２ｍｏｌ／Ｌ〜１．５ｍｏｌ／Ｌがより好ましく、０．３ｍｏｌ／Ｌ〜１．０ｍｏｌ／Ｌがさらに好ましい。そして、タンタル抽出用液調整液としては、硫酸含有量が０．２ｍｏｌ／Ｌ〜１．０ｍｏｌ／Ｌが好ましい。下限値未満ではタンタルの有機溶媒への抽出が不十分になりやすく、上限値を超えるとニオブの有機溶媒への抽出割合が増えてしまうからである。これらの点を考慮すると、硫酸含有量は０．３ｍｏｌ／Ｌ〜０．８ｍｏｌ／Ｌが好ましい。また、タンタル抽出用液調整液としては、タンタルとニオブの合計含有量が３０ｇ／Ｌ〜７００ｇ／Ｌが好ましい。当該合計含有量が下限値未満の液調整液を用いる場合、必要になる液調製液の液量が多くなるところ、当該液調製液における過剰のフッ化水素酸含有量および硫酸含有量を前記好適範囲にするためには多量のフッ化水素酸、硫酸および水が必要になるなど、コスト高になるからである。他方、上記合計含有量が上限値を超える液調整液では、これを溶媒抽出に供用したときに液調整液の流量を有機溶媒の流量に比べて非常に少なくしなければならず、操業が不安定になりやすからである。これらの点を考慮すると、上記合計含有量は、５０ｇ／Ｌ〜５００ｇ／Ｌがより好ましく、１００ｇ／Ｌ〜４００ｇ／Ｌがさらに好ましい。さらに、タンタル抽出用液調整液としてはニオブの含有量が３０ｇ／Ｌ以上が好ましい。当該量未満では、次の液調製工程においてニオブ抽出用液調整液を調製する際、必要になる液調製液の液量が多くなるところ、得ようとしているニオブ抽出用液調製液における過剰のフッ化水素酸含有量および硫酸含有量を前記好適範囲にするためには多量のフッ化水素酸、硫酸および水が必要になるなど、コスト高になるからである。この点を考慮すると、ニオブの含有量は５０ｇ／Ｌ以上がより好ましく、１００ｇ／Ｌ以上がさらに好ましい。 The tantalum extraction step of solvent extraction will be described more specifically. As the tantalum extraction liquid adjusting solution used in this step, the excess hydrofluoric acid content is 0.1 mol / L to 2.0 mol / L. Is preferred. This is because if the tantalum is less than the lower limit, extraction of tantalum into the organic solvent tends to be insufficient, and if the upper limit is exceeded, the extraction ratio of niobium into the organic solvent increases. Considering these points, the excess hydrofluoric acid content is more preferably 0.2 mol / L to 1.5 mol / L, and further preferably 0.3 mol / L to 1.0 mol / L. And as a liquid adjustment liquid for tantalum extraction, sulfuric acid content is preferable 0.2 mol / L-1.0 mol / L. This is because if the tantalum is less than the lower limit, extraction of tantalum into the organic solvent tends to be insufficient, and if the upper limit is exceeded, the extraction ratio of niobium into the organic solvent increases. Considering these points, the sulfuric acid content is preferably 0.3 mol / L to 0.8 mol / L. Moreover, as a liquid adjustment liquid for tantalum extraction, the total content of tantalum and niobium is preferably 30 g / L to 700 g / L. When using the liquid adjustment liquid whose total content is less than the lower limit, the amount of the liquid preparation liquid that is required increases, and the excess hydrofluoric acid content and sulfuric acid content in the liquid preparation liquid are preferably used. This is because a large amount of hydrofluoric acid, sulfuric acid, and water are required to make the range, and the cost increases. On the other hand, in the case of the liquid adjustment liquid whose total content exceeds the upper limit, when the liquid adjustment liquid is used for solvent extraction, the flow rate of the liquid adjustment liquid must be very small compared to the flow rate of the organic solvent, and the operation is inefficient. It is because it becomes easy to become stable. Considering these points, the total content is more preferably 50 g / L to 500 g / L, and further preferably 100 g / L to 400 g / L. Further, the niobium content is preferably 30 g / L or more as the tantalum extraction liquid adjusting liquid. If the amount is less than the above amount, the amount of the liquid preparation liquid required when preparing the liquid preparation liquid for niobium extraction in the next liquid preparation step increases. This is because a large amount of hydrofluoric acid, sulfuric acid, and water are required to bring the hydrofluoric acid content and sulfuric acid content into the preferred ranges, resulting in high costs. Considering this point, the niobium content is more preferably 50 g / L or more, and further preferably 100 g / L or more.
また、タンタル抽出工程において、液調整液（Ａ）と有機溶媒（Ｏ）とを接触させる際の流量比（Ｏ／Ａ比）は、タンタル抽出後に得られる有機溶媒中のタンタル含有量が１０ｇ／Ｌ〜８０ｇ／Ｌになるように設定するのが好ましい。当該タンタル含有量の範囲は、液調整液中のタンタルが全量有機溶媒に抽出されるという設定で算出した値である。タンタル抽出工程後に得られる有機溶媒のタンタル含有量が下限値未満になる流量比では、タンタル以外の物質（特にニオブおよびモリブデン）が有機溶媒に抽出されやすく、不純物の含有量を十分に低減できないからである。他方、タンタル含有量が上限値を超える流量比では、得られる有機溶媒の比重および粘度が高くなりすぎ（極端な場合は固化することがあり）、有機溶媒相と水溶液相の分相特性に劣るからである。分相が悪いと、有機溶媒相中に水溶液相の一部が巻き込まれるという現象が生じやすく、このような現象が生ずると不純物の含有量を十分に低減できなくなるといった不具合が生ずる。ただし、液調整液中のタンタル含有量が微量（例えば、０．３ｇ／Ｌ以下）の場合にあっては、流量比（Ｏ／Ａ比）は、上記基準で求められる流量比に拘わらず所定値以上とすることが好ましい。具体的には、当該流量比は０．０３以上が好ましい。タンタル含有量が微量の場合、これ未満ではタンタルの抽出が不十分となりやすく、タンタル抽出残液中にタンタルが混入して高純度のニオブ精製液を得にくいからである。より確実に高純度のニオブ精製液を得るには、当該流量比は０．０５以上がより好ましい。なお、原料がタンタルを含有していない場合、タンタル抽出工程を実施する必要がないので、最初の溶解液の液調整においてニオブ抽出用の液調整液を調製してニオブ抽出を実施することができる。 Moreover, in the tantalum extraction step, the flow rate ratio (O / A ratio) when the liquid adjusting liquid (A) and the organic solvent (O) are brought into contact with each other is such that the tantalum content in the organic solvent obtained after tantalum extraction is 10 g / It is preferable to set it to be L to 80 g / L. The range of the tantalum content is a value calculated with the setting that the entire amount of tantalum in the liquid adjustment liquid is extracted into the organic solvent. At a flow ratio where the tantalum content of the organic solvent obtained after the tantalum extraction step is less than the lower limit, substances other than tantalum (particularly niobium and molybdenum) are easily extracted into the organic solvent, and the impurity content cannot be reduced sufficiently. It is. On the other hand, when the tantalum content exceeds the upper limit, the specific gravity and viscosity of the obtained organic solvent become too high (in some cases, it may solidify), and the phase separation characteristics of the organic solvent phase and aqueous solution phase are poor. Because. If the phase separation is poor, a phenomenon that a part of the aqueous solution phase is caught in the organic solvent phase is likely to occur, and if such a phenomenon occurs, the impurity content cannot be sufficiently reduced. However, when the tantalum content in the liquid adjustment liquid is very small (for example, 0.3 g / L or less), the flow rate ratio (O / A ratio) is predetermined regardless of the flow rate ratio determined by the above criteria. It is preferable that the value be greater than or equal to the value. Specifically, the flow rate ratio is preferably 0.03 or more. This is because when the tantalum content is very small, the tantalum extraction tends to be insufficient if the tantalum content is less than this, and tantalum is mixed into the tantalum extraction residual liquid, making it difficult to obtain a high-purity niobium purified liquid. In order to obtain a highly pure niobium purified solution more reliably, the flow rate ratio is more preferably 0.05 or more. If the raw material does not contain tantalum, there is no need to carry out the tantalum extraction step, so that the liquid adjustment solution for niobium extraction can be prepared and the niobium extraction can be performed in the liquid adjustment of the first solution. .
溶媒抽出のニオブ抽出工程について、より具体的に説明すると、液調整液（Ａ）と有機溶媒（Ｏ）とを接触させる際の流量比（Ｏ／Ａ比）は、ニオブ抽出後に得られる有機溶媒中のニオブ含有量が１０ｇ／Ｌ〜６０ｇ／Ｌになるように設定するのが好ましい。当該ニオブ含有量の範囲は、液調整液中のニオブが全量有機溶媒に抽出されるという設定で算出した値である。抽出工程後に得られる有機溶媒のニオブ含有量が下限値未満になる流量比では、ニオブ以外の不純物（モリブデン等）が有機溶媒に抽出されやすく、不純物の含有量を十分に低減できないからである。他方、ニオブ含有量が上限値を超える流量比では、得られる有機溶媒の比重および粘度が高くなりすぎ（極端な場合は固化することがあり）、有機溶媒相と水溶液相の分相特性に劣るからである。分相が悪いと、有機溶媒相中に水溶液相の一部が巻き込まれるという現象が生じやすく、このような現象が生ずると不純物の含有量を十分に低減できなくなるといった不具合が生ずる。 The niobium extraction step of the solvent extraction will be described more specifically. The flow rate ratio (O / A ratio) when the liquid adjusting liquid (A) and the organic solvent (O) are brought into contact is the organic solvent obtained after the niobium extraction. It is preferable to set so that the content of niobium in the mixture is 10 g / L to 60 g / L. The range of the niobium content is a value calculated with the setting that all the niobium in the liquid adjustment liquid is extracted into the organic solvent. This is because impurities other than niobium (such as molybdenum) are easily extracted into the organic solvent at a flow rate ratio at which the niobium content of the organic solvent obtained after the extraction step is less than the lower limit, and the impurity content cannot be sufficiently reduced. On the other hand, at a flow ratio where the niobium content exceeds the upper limit, the specific gravity and viscosity of the obtained organic solvent become too high (in some cases, it may solidify), and the phase separation characteristics of the organic solvent phase and aqueous solution phase are poor. Because. If the phase separation is poor, a phenomenon that a part of the aqueous solution phase is caught in the organic solvent phase is likely to occur, and if such a phenomenon occurs, the impurity content cannot be sufficiently reduced.
溶媒抽出の洗浄工程について、より具体的に説明すると、洗浄液としては、鉱酸水溶液、その中でも特に硫酸が好ましい。そして、洗浄液が硫酸水溶液の場合、硫酸含有量が２ｍｏｌ／Ｌ〜５ｍｏｌ／Ｌのものが好ましい。硫酸含有量が下限値未満の洗浄液はニオブおよびその他の不純物の抽出能力が高過ぎるものであるところ、このような洗浄液を用いると、当該洗浄液（Ａ）とニオブ抽出工程で得られたニオブ含有有機溶媒（Ｏ）との流量比（Ｏ／Ａ比）が大きくなってしまい、流量制御が難しくなるからである。他方、上記硫酸含有量が上限値を超えると、洗浄液の抽出能力が低く、洗浄液の流量を増やしても不純物が有機溶媒中に残留しやすいからである。 The solvent extraction washing step will be described more specifically. As the washing liquid, a mineral acid aqueous solution, particularly sulfuric acid is preferred. And when a washing | cleaning liquid is sulfuric acid aqueous solution, a thing with a sulfuric acid content of 2 mol / L-5 mol / L is preferable. A cleaning solution having a sulfuric acid content of less than the lower limit is too high for extracting niobium and other impurities. When such a cleaning solution is used, the niobium-containing organic material obtained in the cleaning solution (A) and the niobium extraction step is used. This is because the flow rate ratio (O / A ratio) with the solvent (O) becomes large, and the flow rate control becomes difficult. On the other hand, when the sulfuric acid content exceeds the upper limit, the extraction ability of the cleaning liquid is low, and impurities are likely to remain in the organic solvent even if the flow rate of the cleaning liquid is increased.
溶媒抽出の逆抽出工程について、より具体的に説明すると、洗浄工程で得られたニオブ含有有機溶媒と接触させる逆抽出用の液としては、純水、超純水、アンモニウムイオン含有水溶液、希アンモニア水等を挙げることができる。例えば、溶媒抽出で使用する有機溶媒が４−メチル−２−ペンタノンである場合、接触させる液はこれらの中でも純水または超純水が特に好ましい。ここで、アンモニウムイオン含有水溶液とは、例えば、フッ化アンモニウム水溶液、フッ化水素アンモニウム水溶液のことである。アンモニウムイオン含有水溶液としては、アンモニウムイオン含有量が８ｍｏｌ／Ｌ以下のものが好ましい。当該上限値を超えると、沈澱生成後の洗浄で、フッ素等の陰イオンの低減が困難になるからである。したがって、陰イオンのより確実な低減のためには当該含有量が６ｍｏｌ／Ｌ以下のものがより好ましい。そして、希アンモニア水としては、濃度が２ｍｏｌ／Ｌ以下のものが好ましい。当該上限値を超えると、逆抽出工程において沈澱が生成するおそれが高いからである。したがって、沈澱の生成をより確実に防止するには、含有量が１ｍｏｌ／Ｌ以下のものがより好ましい。その一方で、有機溶媒がトリブチルホスフェートの場合、希アンモニア水やアンモニウムイオン含有水溶液としては、アンモニアまたはアンモニウムイオン含有量（両方を含む場合は合計含有量）が０．１ｍｏｌ／Ｌ以上のものが好ましい。当該下限値未満では、水溶液相へのニオブの抽出が不十分となり、有機溶媒中にニオブが多く残留しやすいからである。したがって、ニオブをより十分に抽出して残留量を確実に少なくするには、当該含有量が０．２ｍｏｌ／Ｌ以上のものがより好ましい。 The back extraction step of solvent extraction will be described more specifically. As the back extraction liquid to be brought into contact with the niobium-containing organic solvent obtained in the washing step, pure water, ultrapure water, ammonium ion-containing aqueous solution, dilute ammonia Water etc. can be mentioned. For example, when the organic solvent used for solvent extraction is 4-methyl-2-pentanone, pure water or ultrapure water is particularly preferable as the contacted liquid. Here, the ammonium ion-containing aqueous solution is, for example, an ammonium fluoride aqueous solution or an ammonium hydrogen fluoride aqueous solution. As the aqueous solution containing ammonium ions, those having an ammonium ion content of 8 mol / L or less are preferable. If the upper limit is exceeded, it is difficult to reduce anions such as fluorine by washing after precipitation. Therefore, in order to reduce the anion more reliably, the content is more preferably 6 mol / L or less. And as dilute ammonia water, a thing with a density | concentration of 2 mol / L or less is preferable. This is because if the upper limit is exceeded, precipitation is likely to occur in the back extraction step. Therefore, in order to prevent the formation of precipitation more reliably, the content is more preferably 1 mol / L or less. On the other hand, when the organic solvent is tributyl phosphate, the aqueous solution containing ammonia or ammonium ions is preferably one having an ammonia or ammonium ion content (total content if both are included) of 0.1 mol / L or more. . This is because if the amount is less than the lower limit, extraction of niobium into the aqueous phase becomes insufficient, and a large amount of niobium tends to remain in the organic solvent. Therefore, in order to extract niobium more sufficiently and to reliably reduce the residual amount, it is more preferable that the content is 0.2 mol / L or more.
溶媒抽出後の沈澱物生成に用いられる沈澱剤としては、例えば、アンモニア、炭酸アンモニウムまたは炭酸水素アンモニウムが用いられる。アンモニアを使用する場合、アンモニアとしては、気体状、液体状、水溶液状のものを使用できるが、取り扱い性に優れるという点でアンモニア水溶液（アンモニア水）がより好ましい。炭酸アンモニウムまたは炭酸水素アンモニウムを使用する場合、これらとしては、固形状、スラリー状、水溶液状のものを使用できるが、より均一な沈澱を生成でき、かつ洗浄によるフッ素含有量の調整がより容易である点で、水溶液状のものがより好ましい。生成された沈澱物をろ過等によって液体から分離する場合にあっては、希薄アンモニア水や水等で沈澱物を洗浄することが好ましい。 For example, ammonia, ammonium carbonate, or ammonium bicarbonate is used as a precipitating agent used to produce a precipitate after solvent extraction. When ammonia is used, gaseous, liquid, or aqueous solution can be used as ammonia, but an aqueous ammonia solution (ammonia water) is more preferable in terms of excellent handleability. When using ammonium carbonate or ammonium hydrogen carbonate, these can be used in the form of solids, slurries, and aqueous solutions. However, more uniform precipitation can be generated and the fluorine content can be easily adjusted by washing. In a certain point, an aqueous solution is more preferable. When the produced precipitate is separated from the liquid by filtration or the like, it is preferable to wash the precipitate with dilute ammonia water or water.
得られた沈澱物の焙焼工程であるが、半値幅が好適範囲である本発明に係る酸化ニオブ粉末を得るためには、沈澱物を一旦３００℃〜４００℃で２時間以上焙焼（先の焙焼）し、その後５００℃〜１２００℃で２時間以上焙焼（後の焙焼）する焙焼工程が好ましい。先の焙焼については、これを２時間以上行わないと酸化ニオブ粉末の半値幅が好適範囲から外れるおそれがあるからであり、後の焙焼については、これを２時間以上行わないと、半値幅が好適範囲の幅よりも幅広になりやすいからである。なお、焙焼時間の上限値は特に限定されるものではないが、先の焙焼や後の焙焼を所定時間を超えて行っても、半値幅を好適範囲にする効果は所定時間行う場合と差がなく、エネルギーの浪費や作業効率の低下を招くことになる。具体的には、先の焙焼の焙焼時間は４８時間以下が好ましく、後の焙焼の焙焼時間は７２時間以下が好ましいということができる。また、後の焙焼における焙焼温度が上記下限値未満であると、酸化ニオブの半値幅が好適範囲の幅よりも幅広になりやすいからであり、上限値を超えると半値幅が逆に好適範囲の幅よりも幅狭になりやすいからである。このような点を考慮すると、後の焙焼における焙焼温度としては、６００℃〜１１００℃がより好ましい。半値幅が好適範囲内にすると、上述したように、各種用途に好適な酸化ニオブ粉末が得られる。 In order to obtain the niobium oxide powder according to the present invention, which is a roasting step of the obtained precipitate, the half-value width is once roasted at 300 ° C. to 400 ° C. for 2 hours or more (first) Roasting step, followed by roasting at 500 ° C. to 1200 ° C. for 2 hours or longer (later roasting) is preferable. This is because the half-width of the niobium oxide powder may be out of the preferred range unless it is performed for 2 hours or more for the previous roasting. This is because the value range tends to be wider than the preferred range. Note that the upper limit of the roasting time is not particularly limited, but the effect of making the full width at half maximum suitable for a predetermined time even if the previous roasting and the subsequent roasting are performed over a predetermined time There is no difference between them and energy is wasted and work efficiency is reduced. Specifically, the roasting time for the previous roasting is preferably 48 hours or less, and the roasting time for the subsequent roasting is preferably 72 hours or less. In addition, if the baking temperature in the subsequent baking is less than the above lower limit, the full width at half maximum of niobium oxide tends to be wider than the preferred range, and if the upper limit is exceeded, the full width at half maximum is preferred. This is because the width tends to be narrower than the range width. Considering such points, the roasting temperature in the subsequent roasting is more preferably 600 ° C to 1100 ° C. When the full width at half maximum is within the preferable range, as described above, niobium oxide powder suitable for various applications can be obtained.
以上の説明から解るように、本発明に係る酸化ニオブ粉末の製造方法としては、半値幅が好適範囲であるものをより確実に得られるという点で、次のような製造方法が好ましい。つまり、ニオブ溶解液から調製された液調整液からタンタルを抽出してニオブ抽出用液調整液を得た後、当該ニオブ抽出用液調整液からニオブ精製液を分離精製する溶媒抽出工程と、得られたニオブ精製液と沈澱剤とを混合して沈澱物を得る沈澱生成工程と、得られた沈澱物の焙焼工程とを有する酸化ニオブ粉末の製造方法において、焙焼工程として、２段階の焙焼工程からなるものを用いることが好ましい。そして、上述したように、第１段階の焙焼（先の焙焼）における焙焼温度よりも第２段階（後の焙焼）における焙焼温度の方が高い方が好ましい。 As can be seen from the above description, the niobium oxide powder production method according to the present invention is preferably the following production method from the viewpoint that a half-value width within a preferred range can be obtained more reliably. That is, after extracting tantalum from a liquid adjustment liquid prepared from a niobium solution to obtain a liquid adjustment liquid for niobium extraction, a solvent extraction step for separating and purifying the niobium purification liquid from the liquid adjustment liquid for niobium extraction, and In the method for producing niobium oxide powder, comprising the step of producing a precipitate by mixing the purified niobium solution and the precipitant to obtain a precipitate, and the step of baking the obtained precipitate, It is preferable to use what consists of a roasting process. And as mentioned above, it is preferable that the roasting temperature in the second stage (subsequent roasting) is higher than the roasting temperature in the first stage roasting (previous roasting).
また、検討した結果、本発明に係る酸化ニオブ粉末をより確実に得るためには、焙焼前の沈澱物のフッ素含有量を所定の値に調整しておくことが好ましい。例えば、ＣｕＫα１線を用いたＸ線回折分析において、２θ＝２０°〜３０°の範囲の最大ピークの半値幅が０．０８°〜０．８°である酸化ニオブ粉末を得るためには、沈澱物中のフッ素含有量を０．０５質量％〜１．０質量％に調整することが好ましく、より確実に得るためには、０．１質量％〜０．９質量％がより好ましい。また、半値幅が０．１°〜０．５°である酸化ニオブ粉末を得るためには、沈澱物中のフッ素含有量を０．２質量％〜０．８質量％に調整することが好ましく、半値幅が０．１５°〜０．４°である酸化ニオブ粉末を得るためには、沈澱物中のフッ素含有量を０．３質量％〜０．７質量％に調整することが好ましい。フッ素含有量の調整方法としては、フッ化ニオブ液（ニオブ精製液）や沈澱剤の濃度を制御する方法等を挙げることができるが、より好適な方法として、沈澱物の洗浄工程における洗浄条件（洗浄回数等）を調整する方法を挙げることができる。なお、以上説明した焙焼前の沈澱物のフッ素含有量の測定では、沈澱物が付着水分を含有している場合、測定前にこれを１０５℃で十分に乾燥した。付着水分の多少によってフッ素含有量が影響されないためである。したがって、ここでいうフッ素含有量は乾燥質量基準のフッ素含有量である。 As a result of the examination, in order to obtain the niobium oxide powder according to the present invention more reliably, it is preferable to adjust the fluorine content of the precipitate before roasting to a predetermined value. For example, in an X-ray diffraction analysis using CuKα 1 line, in order to obtain a niobium oxide powder in which the half width of the maximum peak in the range of 2θ = 20 ° to 30 ° is 0.08 ° to 0.8 °, The fluorine content in the precipitate is preferably adjusted to 0.05% by mass to 1.0% by mass, and more preferably 0.1% by mass to 0.9% by mass in order to obtain more reliably. Moreover, in order to obtain niobium oxide powder having a half width of 0.1 ° to 0.5 °, it is preferable to adjust the fluorine content in the precipitate to 0.2 mass% to 0.8 mass%. In order to obtain niobium oxide powder having a half width of 0.15 ° to 0.4 °, it is preferable to adjust the fluorine content in the precipitate to 0.3 mass% to 0.7 mass%. Examples of the method for adjusting the fluorine content include a niobium fluoride solution (niobium refined solution) and a method for controlling the concentration of the precipitating agent. As a more preferred method, the washing conditions in the washing step of the precipitate ( A method of adjusting the number of times of washing) can be mentioned. In the measurement of the fluorine content of the precipitate before roasting described above, when the precipitate contains adhering moisture, it was sufficiently dried at 105 ° C. before the measurement. This is because the fluorine content is not affected by the amount of adhering moisture. Therefore, the fluorine content here is the fluorine content on a dry mass basis.
このように、本発明に係る酸化ニオブ粉末の製造方法としては、半値幅が好適範囲であるものをより確実に得るためには、次のような製造方法が好ましい。つまり、ニオブ溶解液から調製された液調整液からタンタルを抽出してニオブ抽出用液調整液を得た後、当該ニオブ抽出用液調整液からニオブ精製液を分離精製する溶媒抽出工程と、得られたニオブ精製液と沈澱剤とを混合して沈澱物を得る沈澱生成工程と、得られた沈澱物の焙焼工程とを有する酸化ニオブ粉末の製造方法において、焙焼前の沈澱物を、沈澱物中のフッ素含有量が上記所定量になるまで洗浄することが好ましい。以上の説明からわかるように、上記半値幅が好適範囲である本発明に係る酸化ニオブ粉末を得るには、溶媒抽出後に行われる沈澱物の洗浄工程および／または焙焼工程の条件を好適な条件にすることが重要であると考えられる。 Thus, as a manufacturing method of the niobium oxide powder according to the present invention, the following manufacturing method is preferable in order to more surely obtain a niobium oxide having a suitable half width. That is, after extracting tantalum from a liquid adjustment liquid prepared from a niobium solution to obtain a liquid adjustment liquid for niobium extraction, a solvent extraction step for separating and purifying the niobium purification liquid from the liquid adjustment liquid for niobium extraction, and In the method for producing niobium oxide powder, comprising the step of producing a precipitate by mixing the purified niobium solution and the precipitating agent to obtain a precipitate, and the step of roasting the obtained precipitate. Washing is preferably performed until the fluorine content in the precipitate reaches the predetermined amount. As can be seen from the above description, in order to obtain the niobium oxide powder according to the present invention in which the half width is in a suitable range, the conditions for the washing step and / or the roasting step of the precipitate performed after the solvent extraction are suitable conditions. Is considered important.
次に、より流動性および均一混合性に優れる酸化ニオブ粉末を製造するという観点から、本発明に係る酸化ニオブ粉末のこれらの特性について、より詳細に検討した。その結果、フッ素含有量の大小によって流動性や均一混合性が変化することが解った。そこで、これらの特性とフッ素含有量との関係について検討したところ、本発明に係る酸化ニオブ粉末としては、フッ素の含有量が３０００質量ｐｐｍ以下のものが好ましく、５００質量ｐｐｍ以下のものがより好ましく、１００質量ｐｐｍ以下のものがさらに好ましかった。 Next, these characteristics of the niobium oxide powder according to the present invention were examined in more detail from the viewpoint of producing a niobium oxide powder having better fluidity and uniform mixing properties. As a result, it was found that the fluidity and uniform mixing properties change depending on the fluorine content. Therefore, when the relationship between these characteristics and the fluorine content was examined, the niobium oxide powder according to the present invention preferably has a fluorine content of 3000 ppm by mass or less, more preferably 500 ppm by mass or less. More preferred is 100 ppm by mass or less.
また、本発明に係る酸化ニオブ粉末を各種用途で用いた結果に基づき、本発明に係る酸化ニオブ粉末について検討した。その結果、例えば光学ガラス用途では、製造された個々の光学ガラスにおける短波長の光の透過率に、実用上問題ない程度であるが、ばらつきがあった。また、ニオブ酸リチウム結晶の製造用途では、いくつかの例で引き上げ時に発生する「ねじれ」の発生が見られた。そこで、短波長光透過率に優れるという観点および「ねじれ」が発生しにくいという観点で検討したところ、本発明に係る酸化ニオブ粉末としては、さらに、モリブデンの含有量が２０質量ｐｐｍ以下であるものが好ましく、１０質量ｐｐｍ以下であるものがより好ましく、１質量ｐｐｍ以下であるものがさらに好ましかった。 Moreover, based on the result of using the niobium oxide powder according to the present invention in various applications, the niobium oxide powder according to the present invention was examined. As a result, for example, in optical glass applications, the transmittance of short-wavelength light in each manufactured optical glass is not problematic in practice, but has variations. In addition, in the production application of lithium niobate crystals, in some cases, the occurrence of “twist” that occurs during pulling was observed. Then, when it examined from the viewpoint that it is excellent in short wavelength light transmittance, and the viewpoint that "twisting" does not occur easily, the niobium oxide powder according to the present invention further has a molybdenum content of 20 mass ppm or less. Is more preferable, 10 ppm or less is more preferable, and 1 ppm or less is more preferable.
そこで、モリブデンの含有量が低い酸化ニオブ粉末を製造することについて検討した。その結果、先に説明したニオブ抽出工程に供用するニオブ抽出用液調整液としては、過剰のフッ化水素酸の含有量（ＨＦ含有量）が２ｍｏｌ／Ｌ〜８ｍｏｌ／Ｌのものがより好ましい。下限値未満では、溶媒抽出におけるニオブの抽出が不十分になりやすいからである。他方、上限値を超えると、モリブデンが抽出されやすくなってしまい、溶媒抽出によるモリブデン含有量の低減が不十分になりやすいからである。したがって、これらの点を考慮すると、ニオブ抽出工程に供用するニオブ抽出用液調整液としては、過剰のフッ化水素酸の含有量が２．５ｍｏｌ／Ｌ〜７ｍｏｌ／Ｌのものがより好ましく、３ｍｏｌ／Ｌ〜６ｍｏｌ／Ｌのものがさらに好ましい。 Therefore, production of niobium oxide powder having a low molybdenum content was studied. As a result, the niobium extraction liquid adjusting solution used in the niobium extraction step described above preferably has an excess hydrofluoric acid content (HF content) of 2 mol / L to 8 mol / L. This is because if it is less than the lower limit, niobium extraction in the solvent extraction tends to be insufficient. On the other hand, when the upper limit is exceeded, molybdenum is easily extracted, and the reduction of the molybdenum content by solvent extraction tends to be insufficient. Therefore, in consideration of these points, the liquid adjusting solution for niobium extraction used in the niobium extraction step is preferably one having an excessive hydrofluoric acid content of 2.5 mol / L to 7 mol / L, more preferably 3 mol. More preferred is / L to 6 mol / L.
また、ニオブ抽出用液調整液としては、硫酸含有量が１ｍｏｌ／Ｌ〜６ｍｏｌ／Ｌのものがより好ましい。下限値未満ではニオブの抽出が不十分になりやすいからである。他方、上限値を超えるとモリブデンが抽出されやすくなってしまい、モリブデン含有量の低減が不十分になりやすいからである。これらの点を考慮すると、モリブデン含有量が低い酸化ニオブ粉末を製造する場合、ニオブ抽出工程に供用するニオブ抽出用液調整液としては、硫酸含有量が１．５ｍｏｌ／Ｌ〜５ｍｏｌ／Ｌのものがより好ましい。 Moreover, as a liquid adjustment liquid for niobium extraction, a thing with a sulfuric acid content of 1 mol / L-6 mol / L is more preferable. This is because niobium is likely to be insufficiently extracted below the lower limit. On the other hand, if the upper limit is exceeded, molybdenum is likely to be extracted and the molybdenum content is likely to be insufficiently reduced. Considering these points, when producing niobium oxide powder with a low molybdenum content, the niobium extraction liquid adjusting solution used in the niobium extraction step has a sulfuric acid content of 1.5 mol / L to 5 mol / L. Is more preferable.
さらに、ニオブ抽出用液調整液としては、ニオブの含有量が３０ｇ／Ｌ〜３５０ｇ／Ｌが好ましい。当該合計含有量が下限値未満の液調整液を用いる場合、必要になる液調製液の液量が多くなるところ、当該液調製液における過剰のフッ化水素酸含有量および硫酸含有量を前記好適範囲にするためには多量のフッ化水素酸、硫酸および水が必要になるなど、コスト高になるからである。他方、上記合計含有量が上限値を超える液調整液では、これを溶媒抽出に供用したときに液調整液の流量を有機溶媒の流量に比べて非常に少なくしなければならず、操業が不安定になりやすからである。これらの点を考慮すると、上記含有量は、５０ｇ／Ｌ〜３００ｇ／Ｌがより好ましく、１００ｇ／Ｌ〜２５０ｇ／Ｌがさらに好ましい。 Further, the niobium extraction liquid adjusting solution preferably has a niobium content of 30 g / L to 350 g / L. When using the liquid adjustment liquid whose total content is less than the lower limit, the amount of the liquid preparation liquid that is required increases, and the excess hydrofluoric acid content and sulfuric acid content in the liquid preparation liquid are preferably used. This is because a large amount of hydrofluoric acid, sulfuric acid, and water are required to make the range, and the cost increases. On the other hand, in the case of the liquid adjustment liquid whose total content exceeds the upper limit, when the liquid adjustment liquid is used for solvent extraction, the flow rate of the liquid adjustment liquid must be very small compared to the flow rate of the organic solvent, and the operation is inefficient. It is because it becomes easy to become stable. Considering these points, the content is more preferably 50 g / L to 300 g / L, and further preferably 100 g / L to 250 g / L.
なお、ニオブ抽出工程に供用するニオブ抽出用液調整液の過剰のフッ化水素酸の含有量、硫酸含有量およびニオブ含有量の調整は、例えば、ニオブ抽出工程前に必要に応じて行われる液調製工程において、タンタル抽出工程で得られた残液（水溶液相）に、必要に応じてフッ化水素酸、フッ化水素酸以外の鉱酸（例えば硫酸）あるいは水を加えることによって調製することができる。 The adjustment of the excess hydrofluoric acid content, sulfuric acid content, and niobium content of the liquid adjustment liquid for niobium extraction used in the niobium extraction process is performed, for example, as necessary before the niobium extraction process. In the preparation step, the residual liquid (aqueous solution phase) obtained in the tantalum extraction step can be prepared by adding hydrofluoric acid, mineral acid other than hydrofluoric acid (for example, sulfuric acid) or water as necessary. it can.
ところで、溶媒抽出の洗浄工程の条件を整えると不純物を除去できることについては、先に説明したが、検討の結果、洗浄工程における不純物除去効果は、モリブデンの除去に特に有効であることが解った。すなわち、洗浄工程における洗浄液としては、先にも説明したが、鉱酸水溶液、その中でも特に硫酸が好ましく、洗浄液が硫酸水溶液の場合、硫酸含有量が２ｍｏｌ／Ｌ〜５ｍｏｌ／Ｌのものが好ましい。先に説明したように、硫酸含有量が下限値未満の洗浄液はニオブ抽出能力が高過ぎるものであるところ、このような洗浄液を用いると、当該洗浄液（Ａ）と抽出工程で得られたニオブ含有有機溶媒（Ｏ）との流量比（Ｏ／Ａ比）が大きくなってしまい、流量制御が難しくなるからである。例えば流量比が大きい状況では、洗浄液の流量が適量より少ないと、わずかに少ない場合でも、有機溶媒中のモリブデンの洗浄液への抽出が不充分となると共に有機溶媒中のモリブデン残留量が多くなってしまう。逆に、洗浄液の流量が適量より多いと、わずかに多い場合でも、有機溶媒中から洗浄液中に抽出されるニオブの割合が多くなってしまい、ニオブの損失となりやすい。他方、洗浄液における硫酸含有量が上限値を超えると、洗浄液の抽出能力が低く、洗浄液の流量を増やしてもモリブデンが有機溶媒中に残留しやすいからである。これらの点を考慮すると、洗浄液が硫酸水溶液の場合、硫酸含有量は２．５ｍｏｌ／Ｌ〜４ｍｏｌ／Ｌがより好ましい。なお、洗浄工程において洗浄液と有機溶媒とを接触させる際の流量比（Ｏ／Ａ比）は、０．５〜８が好ましい。下限値未満では、洗浄されるニオブ量が増えてしまい、上限値を超えると、モリブデンの除去が不十分になるからである。これらの点を考慮すると、当該流量比（Ｏ／Ａ比）は１〜５がより好ましい。 By the way, as described above, the impurities can be removed by adjusting the conditions of the solvent extraction washing step. As a result of the examination, it was found that the impurity removal effect in the washing step is particularly effective for removing molybdenum. That is, as described above, the cleaning liquid in the cleaning step is preferably a mineral acid aqueous solution, and sulfuric acid is particularly preferable. When the cleaning liquid is a sulfuric acid aqueous solution, the sulfuric acid content is preferably 2 mol / L to 5 mol / L. As described above, a cleaning solution having a sulfuric acid content less than the lower limit has a niobium extraction capability that is too high. When such a cleaning solution is used, the cleaning solution (A) and the niobium-containing product obtained in the extraction step are used. This is because the flow rate ratio (O / A ratio) with the organic solvent (O) becomes large, and the flow rate control becomes difficult. For example, in a situation where the flow rate ratio is large, if the flow rate of the cleaning solution is less than an appropriate amount, even if the flow rate is slightly small, extraction of molybdenum in the organic solvent into the cleaning solution is insufficient and the residual amount of molybdenum in the organic solvent increases. End up. On the other hand, if the flow rate of the cleaning liquid is larger than an appropriate amount, even if it is slightly higher, the ratio of niobium extracted from the organic solvent into the cleaning liquid increases, and niobium loss tends to occur. On the other hand, if the sulfuric acid content in the cleaning liquid exceeds the upper limit, the extraction capacity of the cleaning liquid is low, and molybdenum tends to remain in the organic solvent even if the flow rate of the cleaning liquid is increased. Considering these points, when the cleaning liquid is a sulfuric acid aqueous solution, the sulfuric acid content is more preferably 2.5 mol / L to 4 mol / L. In addition, as for the flow rate ratio (O / A ratio) at the time of making a washing | cleaning liquid and an organic solvent contact in a washing | cleaning process, 0.5-8 are preferable. If the amount is less than the lower limit, the amount of niobium to be washed increases, and if the amount exceeds the upper limit, molybdenum removal becomes insufficient. Considering these points, the flow rate ratio (O / A ratio) is more preferably 1 to 5.
ここまでの製造方法の説明では、フッ化水素酸以外の鉱酸として硫酸を用いる場合について説明したが、フッ化水素酸以外の鉱酸として塩酸または硝酸を用いてもよい。この場合、塩酸や硝酸の含有量および洗浄液中の塩酸や硝酸の含有量は、硫酸を用いる場合の２倍である。これは、硫酸１ｍｏｌ／Ｌは塩酸または硝酸では２ｍｏｌ／Ｌと等価だからである。ただし、濃度を硫酸の場合の２倍とした場合、流量は、硫酸の場合と塩酸または硝酸の場合とで変わらない。なお、塩酸は、硫酸に比べて高価であると共に鉄を有機溶媒中に抽出しやすくするという欠点があり、また硝酸は、硫酸に比べて高価であると共に硝酸性窒素を含有するため排水処理コストが高いという欠点があるため、フッ化水素酸以外の酸としては、硫酸が最も好ましい。 In the description of the production method so far, the case where sulfuric acid is used as a mineral acid other than hydrofluoric acid has been described, but hydrochloric acid or nitric acid may be used as a mineral acid other than hydrofluoric acid. In this case, the content of hydrochloric acid and nitric acid and the content of hydrochloric acid and nitric acid in the cleaning liquid are twice that when sulfuric acid is used. This is because 1 mol / L of sulfuric acid is equivalent to 2 mol / L of hydrochloric acid or nitric acid. However, when the concentration is twice that of sulfuric acid, the flow rate does not change between sulfuric acid and hydrochloric acid or nitric acid. Hydrochloric acid is expensive compared to sulfuric acid and has the disadvantages of facilitating extraction of iron into an organic solvent, and nitric acid is expensive compared to sulfuric acid and contains nitrate nitrogen, resulting in wastewater treatment costs. As the acid other than hydrofluoric acid, sulfuric acid is most preferable.
以上の説明から解るように、本発明に係る酸化ニオブ粉末は、流動性および均一混合性に優れるものであり、ガラス（特に光学ガラス）用、セラミック用、薄膜形成材料用さらにはニオブ酸リチウム（ＬＮ）用として好適である。 As can be seen from the above description, the niobium oxide powder according to the present invention is excellent in fluidity and uniform mixing properties, and is for glass (particularly optical glass), for ceramics, for thin film forming materials, and further for lithium niobate ( Suitable for LN).
以下、本発明に係る酸化ニオブの好適な第１実施形態を、図１に示した製造工程のフローを参照しつつ説明する。 Hereinafter, a preferred first embodiment of niobium oxide according to the present invention will be described with reference to the flow of the manufacturing process shown in FIG.
ニオブ含有原料の溶解液の製造
まず、原料としてコロンバイト精鉱（組成はニオブ３９質量％、タンタル１０質量％、モリブデン０．１質量％）を７２００ｋｇ用意した。そして、当該原料に水３５００Ｌを混合し、湿式ボールミルにて粉砕してスラリーを得た（工程１）。このスラリーに、８０質量％フッ化水素酸８８００ｋｇを２０時間かけて添加し（工程２）、添加終了後、得られた溶液を約６０℃に１２時間保持した。その後、溶液に対してろ過・水洗を施した（工程３）。ろ過方法はフィルタープレスであり、水５００Ｌを用いた。そして、ろ液と水洗液とからなるニオブの溶解液１１２００Ｌを得た（工程４）。当該溶解液は、ニオブが２４６ｇ／Ｌ、タンタルが６３ｇ／Ｌ、モリブデンが０．６ｇ／Ｌ、過剰フッ化水素酸（ＨＦ）が０．８ｍｏｌ／Ｌというものであった。
Production of Niobium-containing raw material solution First, 7200 kg of Columbite concentrate (composition: 39% by mass of niobium, 10% by mass of tantalum, 0.1% by mass of molybdenum) was prepared as a raw material. And the water 3500L was mixed with the said raw material, and it grind | pulverized with the wet ball mill, and obtained the slurry (process 1). To this slurry, 8800 kg of 80% by mass hydrofluoric acid was added over 20 hours (Step 2), and after the addition was completed, the resulting solution was held at about 60 ° C. for 12 hours. Thereafter, the solution was filtered and washed (step 3). The filtration method was a filter press, and 500 L of water was used. Then, 11200 L of a niobium solution composed of the filtrate and the washing solution was obtained (step 4). The solution was niobium 246 g / L, tantalum 63 g / L, molybdenum 0.6 g / L, and excess hydrofluoric acid (HF) 0.8 mol / L.
液調製液（タンタル抽出用液調整液）の製造
そして、得られたニオブ溶解液に９６％（１８ｍｏｌ／Ｌ）硫酸３２０Ｌを添加して液調整液を得た（工程５）。当該溶解液は、ニオブが２３９ｇ／Ｌ、タンタルが６１ｇ／Ｌ、モリブデンが０．６ｇ／Ｌ、過剰フッ化水素酸（ＨＦ）が０．７８ｍｏｌ／Ｌ、硫酸が０．５ｍｏｌ／Ｌというものであった。
Production of liquid preparation liquid (liquid adjustment liquid for tantalum extraction) and 320 L of 96% (18 mol / L) sulfuric acid was added to the obtained niobium solution to obtain a liquid adjustment liquid (Step 5). The solution is niobium 239 g / L, tantalum 61 g / L, molybdenum 0.6 g / L, excess hydrofluoric acid (HF) 0.78 mol / L, and sulfuric acid 0.5 mol / L. there were.
なお、ニオブ溶解液や液調整液におけるニオブ（Ｎｂ）、タンタル（Ｔａ）およびモリブデン（Ｍｏ）の含有量については、ＩＣＰ−ＡＥＳ法を用いて測定した。また、過剰フッ化水素酸含有量は、「イオン交換分離−フッ素イオン電極法」を用いて測定した。硫酸含有量は、液調整液の製造に使用した９６％硫酸の使用量から算出した。なお、液調整液の硫酸濃度については、確認のため、ＩＣＰ−ＡＥＳにてＳ（硫黄）を測定して硫酸に換算する方法によっても測定したが、９６％硫酸の使用量から算出した値とほぼ同じであったため、表１には９６％硫酸（中和滴定の結果１８．０ｍｏｌ／Ｌであった）の使用量から算出した値を記載した。 The contents of niobium (Nb), tantalum (Ta), and molybdenum (Mo) in the niobium solution and liquid adjustment solution were measured using the ICP-AES method. Moreover, excess hydrofluoric acid content was measured using "ion exchange separation-fluorine ion electrode method". The sulfuric acid content was calculated from the amount of 96% sulfuric acid used for the production of the liquid adjustment solution. In addition, about the sulfuric acid concentration of a liquid adjustment liquid, although it measured also by the method of measuring S (sulfur) in ICP-AES and converting into sulfuric acid for confirmation, the value calculated from the usage-amount of 96% sulfuric acid and Since they were almost the same, Table 1 shows values calculated from the use amount of 96% sulfuric acid (the result of neutralization titration was 18.0 mol / L).
溶媒抽出
まず、得られた液調整液（タンタル抽出用液調整液）から溶媒抽出によってタンタルを抽出して残液（ニオブ含有）を得た（工程６、タンタル抽出工程）。タンタルの抽出ではミキサーセトラー抽出装置を用いた。ミキサーセトラーの段数は７段であり（図２参照）、セトラー部の容量はいずれも１５０Ｌであった。また、溶媒抽出に用いた有機溶媒は４−メチル−２−ペンタノン（ＭＩＢＫ）であった。そして、液調整液（タンタル抽出用液調整液）の流量は、２．３Ｌ／分であり、有機溶媒（ＭＩＢＫ）の流量は４．５Ｌ／分であった。
Solvent extraction First, tantalum was extracted from the obtained liquid adjustment liquid (tantalum extraction liquid adjustment liquid) by solvent extraction to obtain a residual liquid (containing niobium) (step 6, tantalum extraction step). In the extraction of tantalum, a mixer-settler extraction device was used. The number of stages of the mixer settler was 7 (see FIG. 2), and the capacity of the settler part was 150 L in all cases. The organic solvent used for solvent extraction was 4-methyl-2-pentanone (MIBK). The flow rate of the liquid adjustment liquid (tantalum extraction liquid adjustment liquid) was 2.3 L / min, and the flow rate of the organic solvent (MIBK) was 4.5 L / min.
そして、得られた残液に、所定量の８０％フッ化水素酸と９６％硫酸を加えて、複数種類のニオブ抽出用液調整液（Ａ〜Ｄ）を得た（工程７）。ニオブ抽出用液調製液Ａ（１２５００Ｌ）は、得られたニオブ抽出用液調整液から分取した１００００Ｌと、８０％フッ化水素酸８５０ｋｇと、９６％硫酸１８００Ｌとを混合したものである。液調製液Ｂ（４８４Ｌ）は、得られたニオブ抽出用液調整液から分取した３００Ｌと、８０％フッ化水素酸７０ｋｇと、９６％硫酸１２６Ｌとを混合したものである。液調製液Ｃ（５７９Ｌ）は、得られたニオブ抽出用液調整液から分取した３００Ｌと、８０％フッ化水素酸１１３ｋｇと、９６％硫酸１８５Ｌとを混合したものである。液調製液Ｄ（６８３Ｌ）は、得られたニオブ抽出用液調整液から分取した３００Ｌと、８０％フッ化水素酸１５１ｋｇと、９６％硫酸２５７Ｌとを混合したものである。各ニオブ抽出用液調整液のニオブ含有量等は、次の表１に示されるとおりであった。 Then, a predetermined amount of 80% hydrofluoric acid and 96% sulfuric acid were added to the obtained residual liquid to obtain a plurality of types of niobium extraction liquid adjustment liquids (A to D) (step 7). Niobium extraction liquid preparation liquid A (12500 L) is a mixture of 10000 L fractioned from the obtained niobium extraction liquid adjustment liquid, 850 kg of 80% hydrofluoric acid, and 1800 L of 96% sulfuric acid. The liquid preparation liquid B (484 L) is a mixture of 300 L fractioned from the obtained niobium extraction liquid adjustment liquid, 70 kg of 80% hydrofluoric acid, and 126 L of 96% sulfuric acid. The liquid preparation liquid C (579 L) is a mixture of 300 L fractioned from the obtained liquid adjustment liquid for niobium extraction, 113 kg of 80% hydrofluoric acid, and 185 L of 96% sulfuric acid. Liquid preparation liquid D (683 L) is a mixture of 300 L fractioned from the obtained liquid adjustment liquid for niobium extraction, 151 kg of 80% hydrofluoric acid, and 257 L of 96% sulfuric acid. The niobium content and the like of each niobium extraction liquid adjusting solution was as shown in Table 1 below.
次に、得られたニオブ抽出用液調製液Ａ〜Ｄから溶媒抽出によってニオブ精製液（フッ化ニオブ液）を得た。ニオブ抽出用液調製液からニオブ精製液を得る工程は、ニオブ抽出工程（工程８）と、洗浄工程（工程９）と、ニオブの逆抽出工程（工程１０）とからなるものであった。これらの工程ではミキサーセトラー抽出装置を用いた。ミキサーセトラーの段数は、ニオブ抽出工程では７段、洗浄工程および逆抽出工程では１０段であった（図３参照）。セトラー部の容量はいずれも１５０Ｌであった。そして、溶媒抽出に用いた有機溶媒は４−メチル−２−ペンタノン（ＭＩＢＫ）であった。さらに、洗浄工程で用いた洗浄液（希硫酸）は、９６％硫酸（１８ｍｏｌ／Ｌ）と純水とを混合して調製したものであり、調製後、得られた洗浄液の硫酸濃度を中和滴定にて確認した。各工程の条件および得られたニオブ精製液の組成を表２に示す。 Next, a niobium purified liquid (niobium fluoride liquid) was obtained from the obtained niobium extraction liquid preparation liquids A to D by solvent extraction. The step of obtaining a niobium purified solution from the liquid preparation solution for niobium extraction consisted of a niobium extraction step (step 8), a washing step (step 9), and a niobium back extraction step (step 10). In these steps, a mixer settler extraction apparatus was used. The number of stages of the mixer settler was 7 in the niobium extraction process and 10 in the washing process and the back extraction process (see FIG. 3). The capacity of the settler part was 150 L in all cases. The organic solvent used for solvent extraction was 4-methyl-2-pentanone (MIBK). Furthermore, the cleaning liquid (dilute sulfuric acid) used in the cleaning process was prepared by mixing 96% sulfuric acid (18 mol / L) and pure water. After the preparation, the sulfuric acid concentration of the resulting cleaning liquid was neutralized by titration. Confirmed. Table 2 shows the conditions of each step and the composition of the obtained niobium purified solution.
実施例１：ニオブ抽出用液調整液Ａから得たニオブ精製液から分取した２４４Ｌ（ニオブ５０ｋｇ相当）に純水を加えて、希釈液１０００Ｌ（ニオブ５０ｇ／Ｌ）を得た。この希釈液に蒸気を吹き込んで５０℃に昇温させた後、希釈液を撹拌しながら当該希釈液中にアンモニア水２３０Ｌ（１３．５ｍｏｌ／Ｌ）を２０Ｌ／分の添加速度で添加して沈澱物を生成させ、添加終了後３０分間撹拌を継続した（工程１１）。なお、撹拌終了後のｐＨは９．３であった（なお、以後すべての実施例および比較例において撹拌終了時のｐＨは９．０〜９．４であった）。撹拌終了後、沈澱物を含む溶液に洗浄を施した（工程１２）。当該洗浄工程は、溶液が入った容器を６時間静置して沈澱物を沈降させ、容器の上澄み液を抜出し、その後洗浄液を所定量添加して、添加終了後３０分間撹拌を行うという工程を所定回数繰り返すというものであった。洗浄液は０．５ｍｏｌ／Ｌアンモニア水であった。洗浄液の使用量および洗浄の繰り返し回数については、表３に示されるとおりであった。洗浄工程における最後の３０分間の撹拌後、得られたスラリーを真空ろ過装置を用いてろ過し、ケーキを得た（工程１３）。得られたケーキを石英皿に載せて焙焼炉（ガス炉）に入れて３５０℃にて５時間焙焼した後、さらに９００℃で１５時間焙焼した（工程１４）。そして、得られた焙焼品を振動ミルで粉砕して（工程１５）、酸化ニオブ粉末を得た。 Example 1 : Pure water was added to 244 L (equivalent to 50 kg of niobium) fractionated from the niobium purified solution obtained from the liquid adjustment solution A for niobium extraction to obtain a diluted solution 1000 L (niobium 50 g / L). After the steam was blown into this diluted solution and the temperature was raised to 50 ° C., 230 L (13.5 mol / L) of aqueous ammonia was added to the diluted solution at a rate of addition of 20 L / min while stirring. Stirring was continued for 30 minutes after completion of the addition (step 11). The pH after completion of stirring was 9.3 (hereinafter, the pH at the end of stirring was 9.0 to 9.4 in all Examples and Comparative Examples). After completion of the stirring, the solution containing the precipitate was washed (step 12). In the washing step, the container containing the solution is allowed to stand for 6 hours to settle the precipitate, the supernatant of the container is drawn out, and then a predetermined amount of the washing solution is added, followed by stirring for 30 minutes after completion of the addition. It was to repeat a predetermined number of times. The cleaning liquid was 0.5 mol / L ammonia water. About the usage-amount of the washing | cleaning liquid and the repetition frequency of washing | cleaning, it was as Table 3 showing. After the last 30 minutes of stirring in the washing step, the resulting slurry was filtered using a vacuum filtration device to obtain a cake (step 13). The obtained cake was placed on a quartz plate and placed in a roasting furnace (gas furnace) and roasted at 350 ° C. for 5 hours, and then further roasted at 900 ° C. for 15 hours (step 14). The obtained roasted product was pulverized with a vibration mill (step 15) to obtain niobium oxide powder.
実施例２〜９および比較例１，２：これらの実施例および比較例は、上記実施例１とは、液調整液Ａから得たニオブ精製液を用いた点は同じであるが、洗浄工程（工程１２）の条件が異なる。洗浄条件は表３に示されるとおりである。これら以外の条件は、実施例１と同じであったので、それらの説明は省略する。 Examples 2 to 9 and Comparative Examples 1 and 2 : These Examples and Comparative Examples are the same as Example 1 above, except that the niobium purified liquid obtained from the liquid adjustment liquid A was used, but the washing step The conditions of (Step 12) are different. The cleaning conditions are as shown in Table 3. Since the other conditions were the same as in Example 1, their description is omitted.
実施例１０〜１９および比較例３，４：これらの実施例および比較例は、上記実施例４とは、焙焼工程（工程１４）の第２段階の焙焼における焙焼温度条件が異なる。焙焼条件は表３に示されるとおりである。これら以外の条件は、実施例４と同じであった。 Examples 10 to 19 and Comparative Examples 3 and 4 : These Examples and Comparative Examples differ from the above Example 4 in the roasting temperature conditions in the second stage roasting of the roasting step (Step 14). The roasting conditions are as shown in Table 3. Conditions other than these were the same as in Example 4.
実施例２０〜２７：これらの実施例は、上記実施例４とは、第２段階の焙焼における焙焼温度が異なると共に、洗浄工程（工程１２）の条件が若干異なる（実施例５〜８の洗浄条件に相当）。これ以外の条件は、実施例４と同じであった。 Examples 20 to 27 : These examples differ from the above Example 4 in the roasting temperature in the second stage of roasting and the conditions of the cleaning step (Step 12) are slightly different (Examples 5 to 8). Equivalent to cleaning conditions). The other conditions were the same as in Example 4.
実施例２８〜３０および比較例５〜８：これらの実施例および比較例は、上記実施例４とは、焙焼工程（工程１４）の条件が異なる。焙焼条件は表３に示されるとおりである。これら以外の条件は、実施例４と同じであった。 Examples 28 to 30 and Comparative Examples 5 to 8 : These Examples and Comparative Examples are different from Example 4 in the conditions of the roasting step (Step 14). The roasting conditions are as shown in Table 3. Conditions other than these were the same as in Example 4.
実施例３１〜３３：これらの実施例は、実施例４とは、用いたニオブ精製液の種類と使用液量が異なる（ただし、ニオブ５０ｋｇ相当であることは同じ）。各実施例で用いたニオブ精製液の種類は、表３に示されるとおりである。これ以外の条件は実施例４と同じであった。 Examples 31 to 33 : These examples differ from Example 4 in the type of niobium refined solution used and the amount of liquid used (however, the equivalent to 50 kg of niobium is the same). The types of niobium purification solutions used in each example are as shown in Table 3. The other conditions were the same as in Example 4.
各実施例および比較例で得られた酸化ニオブ粉末について、タンタル（Ｔａ）、モリブデン（Ｍｏ）およびフッ素（Ｆ）の含有量を測定すると共にＸ線回折による分析を行った。また、後述する方法で、均一混合性評価試験、流動性試験（スクリューフィーダ供給試験）、ニオブ酸リチウム単結晶製造試験を行って、それぞれの特性を評価した。各測定結果、分析結果および評価結果は、表４〜６に示されるとおりである。 About the niobium oxide powder obtained in each Example and Comparative Example, the contents of tantalum (Ta), molybdenum (Mo), and fluorine (F) were measured and analyzed by X-ray diffraction. Moreover, by the method mentioned later, the homogeneity evaluation test, the fluidity test (screw feeder supply test), and the lithium niobate single crystal manufacturing test were performed, and each characteristic was evaluated. Each measurement result, analysis result, and evaluation result are as shown in Tables 4-6.
ニオブ（Ｎｂ）およびモリブデン（Ｍｏ）の含有量については、フッ化水素酸溶解−イオン交換分離−ＩＣＰ−ＡＥＳ法によって測定した。なお、各実施例および比較例の酸化ニオブ粉末におけるタンタル（Ｔａ）の含有量は、いずれも５ｐｐｍ以下と良好であったので、表への掲載を省略した。また、フッ素含有量であるが、各実施例の酸化ニオブ粉末や比較例１，４の酸化ニオブ粉末については、熱加水分解ランタン・アリザリンコンプレクソン吸光光度法（ＪＩＳ Ｈ １６９８-1976（ニオブ中のフッ素定量方法））に準拠する方法で測定し、比較例２，３の酸化ニオブ粉末や、各実施例および比較例における中間生成物である沈澱物（洗浄後のろ過ケーキを分取して１０５℃にて５時間乾燥させた試料）については、「アルカリ溶融−温水抽出−イオン電極法」を用いて測定した。 The contents of niobium (Nb) and molybdenum (Mo) were measured by hydrofluoric acid dissolution-ion exchange separation-ICP-AES method. In addition, since the content of tantalum (Ta) in the niobium oxide powders of the respective examples and comparative examples was as good as 5 ppm or less, it was omitted from the table. Moreover, although it is fluorine content, about the niobium oxide powder of each Example and the niobium oxide powder of Comparative Examples 1 and 4, thermal hydrolysis lanthanum-alizarin complexone spectrophotometry (JIS H 1698-1976 (in niobium) Measured by a method in accordance with the fluorine determination method)), the niobium oxide powder of Comparative Examples 2 and 3 and the precipitate (the filter cake after washing) as an intermediate product in each Example and Comparative Example Samples dried at 5 ° C. for 5 hours were measured using an “alkali melt-hot water extraction-ion electrode method”.
Ｘ線回折測定
酸化にオブ粉末についてＸ線回折装置（ＭＸＰ１８：マックサイエンス（株）製）を用いて測定を行った。ここでは、銅（Ｃｕ）ターゲットを使用し、Ｃｕ−Ｋα１線による回折Ｘ線強度を測定した。そして、その他の測定条件は、管電圧４０ｋＶ、管電流１５０ｍＡ、測定範囲２θ＝１０°〜９０°、サンプリング幅０．０２°、走査速度４．０°／分であった。測定の結果、２０°〜３０°の範囲に強いピークが現れることが解った。同定の結果、この範囲に出現する強いピークは酸化ニオブの存在を示すものであった。そこで、ピークの出現位置を分析したところ、強いピークが出現する位置は次の３つの位置すなわち、２θ＝２２．６°±０．５°の位置、２θ＝２３．２°〜２６．２°の位置および２θ＝２８．４°±０．４°の位置であることが解った。２θ＝２２．６°±０．５°の位置および２θ＝２８．４°±０．４°の位置にピークが出現している例として実施例４のＸＲＤ測定結果を図４に示し、２θ＝２３．２°〜２６．２°の位置にピークが出現している例として実施例１６のＸＲＤ測定結果を図５に示した。そして、ピーク強度について分析したところ、２θ＝２２．６°±０．５°の位置および２θ＝２８．４°±０．４°の位置のピークの強度が強くなると２θ＝２３．２°〜２６．２°の位置のピークの強度が弱くなり、逆に２θ＝２３．２°〜２６．２°の位置のピークの強度が強くなると２θ＝２２．６°±０．５°の位置および２θ＝２８．４°±０．４°の位置のピークの強度が弱くなるという傾向があることが解った。また、２０°〜３０°の範囲に出現したピークのうち最も強いピークを用いてピーク半値幅の求めた（ＪＩＳ Ｋ ０１３１−1996「Ｘ線回折分析通則」の図６等参照）。さらに、２θ＝２２．６°±０．５°の位置または２θ＝２８．４°±０．４°の位置に出現したピークのうち最も強いピークｐ（ピーク強度Ｐ）と、２θ＝２３．２°〜２６．２°の位置に出現したピークのうち最も強いピークｑ（ピーク強度Ｑ）について、ピーク強度比（Ｑ／Ｐ）を求めた。
X-ray diffraction measurement Oxide powder was measured for oxidation using an X-ray diffractometer (MXP18: manufactured by Mac Science Co., Ltd.). Here, a copper (Cu) target was used, and the diffraction X-ray intensity by the Cu-Kα 1 line was measured. Other measurement conditions were a tube voltage of 40 kV, a tube current of 150 mA, a measurement range 2θ = 10 ° to 90 °, a sampling width of 0.02 °, and a scanning speed of 4.0 ° / min. As a result of the measurement, it was found that a strong peak appears in the range of 20 ° to 30 °. As a result of identification, a strong peak appearing in this range indicates the presence of niobium oxide. Therefore, when the appearance position of the peak is analyzed, the position where the strong peak appears is the following three positions: 2θ = 22.6 ° ± 0.5 °, 2θ = 23.2 ° to 26.2 °. And 2θ = 28.4 ° ± 0.4 °. As an example in which peaks appear at the position of 2θ = 22.6 ° ± 0.5 ° and at the position of 2θ = 28.4 ° ± 0.4 °, the XRD measurement result of Example 4 is shown in FIG. FIG. 5 shows the XRD measurement result of Example 16 as an example in which a peak appears at a position of = 23.2 ° to 26.2 °. As a result of analyzing the peak intensity, when the intensity of the peak at the position 2θ = 22.6 ° ± 0.5 ° and the position 2θ = 28.4 ° ± 0.4 ° is increased, 2θ = 23.2 °- When the intensity of the peak at the position of 26.2 ° becomes weak, and conversely, the intensity of the peak at the position of 2θ = 23.2 ° to 26.2 ° becomes strong, the position of 2θ = 22.6 ° ± 0.5 ° and It was found that the peak intensity at the position of 2θ = 28.4 ° ± 0.4 ° tends to be weak. Moreover, the peak half-value width was determined using the strongest peak among the peaks that appeared in the range of 20 ° to 30 ° (see FIG. 6 and the like in JIS K 0131-1996 “General Rules for X-ray Diffraction Analysis”). Further, the strongest peak p (peak intensity P) among the peaks appearing at the position of 2θ = 22.6 ° ± 0.5 ° or the position of 2θ = 28.4 ° ± 0.4 °, and 2θ = 23. The peak intensity ratio (Q / P) was determined for the strongest peak q (peak intensity Q) among the peaks that appeared at 2 ° to 26.2 °.
均一混合性評価試験
酸化ニオブ粉末の均一混合性を次のようにして評価した。まず、各実施例や比較例で得られた酸化ニオブ粉末８５７ｇと９９．９９％炭酸リチウム１４３ｇとをラボミキサＬＶ−１型（ホソカワミクロン社製）の混合容器に入れて、スクリュー回転数１５０ｒｐｍにて１分間混合し、混合後、得られた混合物（第１サンプル）をサンプリングした。その後、さらにスクリュー回転数１５０ｒｐｍにて４分間混合（合計５分間混合）し、得られた混合物（第２サンプル）をサンプリングした。そして、低真空走査電子顕微鏡ＪＳＭ−５５１０ＬＶ（日本電子株式会社製）を用いて、加速電圧１５ｋＶ、拡大率１０００倍、試料室真空度３０Ｐａの反射電子組成像にて混合状態を観察し、両サンプルとも均一な混合状態であった場合は「◎」と、第１サンプルの混合状態は不均一であるが第２サンプルの混合状態は均一であった場合は「○」と、いずれのサンプルの混合状態とも不均一であった場合は「×」と評価した。
Uniform mixing evaluation test The uniform mixing of the niobium oxide powder was evaluated as follows. First, 857 g of niobium oxide powder obtained in each example and comparative example and 143 g of 99.99% lithium carbonate were put into a mixing vessel of a laboratory mixer LV-1 type (manufactured by Hosokawa Micron), and 1 at a screw rotation speed of 150 rpm. After mixing for a minute, the resulting mixture (first sample) was sampled. Thereafter, the mixture was further mixed for 4 minutes at a screw rotation speed of 150 rpm (mixed for a total of 5 minutes), and the resulting mixture (second sample) was sampled. Then, using a low vacuum scanning electron microscope JSM-5510LV (manufactured by JEOL Ltd.), the mixed state was observed with a reflected electron composition image having an acceleration voltage of 15 kV, an enlargement ratio of 1000 times, and a sample chamber vacuum degree of 30 Pa. In both cases, “◎” indicates that the mixed state is uniform, and “○” indicates that the mixed state of the first sample is non-uniform but the mixed state of the second sample is uniform. When the state was not uniform, it was evaluated as “x”.
流動性試験
酸化ニオブ粉末の流動性を、スクリューフィーダにおける供給性に基づいて評価した。まず、スクリュー径１０ｍｍのスクリューフィーダのホッパー（容量１Ｌの位置に印があるもの）に、当該印の位置まで酸化ニオブ粉末を入れてスクリューフィーダの運転をスクリュー回転数６０ｒｐｍで開始する。そして、運転開始から３分経過後、フィーダの排出口に設置していた受け容器の第１回目の交換を行い、以後、２０分経過する毎に受け容器を交換すると共に５分経過する毎にホッパーの印の位置まで酸化ニオブ粉末を注ぎ足す。このような作業を行いつつスクリューフィーダを１８３分間運転する。そして、最初の３分間を除き、その後に設置された各受け容器に溜まった酸化ニオブ粉末の量（排出量）を、各受け容器毎に測定する。測定の結果、全ての容器内の酸化ニオブ粉末量（フィーダ排出量）が４００ｇ以上あった場合は「◎」と、全ての容器内の酸化ニオブ粉末量が２００ｇ以上であった場合は「○」と、途中で排出しなくなった場合は「×」と評価した。
Flowability test The flowability of the niobium oxide powder was evaluated based on the feedability in the screw feeder. First, niobium oxide powder is put in the hopper of a screw feeder having a screw diameter of 10 mm (marked at the position of 1 L capacity) to the position of the mark, and the operation of the screw feeder is started at a screw rotational speed of 60 rpm. After 3 minutes from the start of operation, the receiving container installed at the feeder outlet is replaced for the first time. After that, every 20 minutes, the receiving container is replaced and every 5 minutes Add niobium oxide powder to the hopper mark. The screw feeder is operated for 183 minutes while performing such operations. Then, except for the first 3 minutes, the amount (discharge amount) of the niobium oxide powder accumulated in each receiving container installed thereafter is measured for each receiving container. As a result of measurement, when the amount of niobium oxide powder in all containers (feeder discharge amount) is 400 g or more, “◎”, and when the amount of niobium oxide powder in all containers is 200 g or more, “◯”. And when it stopped discharging on the way, it evaluated as "x".
ニオブ酸リチウム単結晶製造試験
また、実施例１，４，１８，２３〜２５で得られた酸化ニオブ粉末を用いてニオブ酸リチウム単結晶（ＬＮ単結晶）を製造した。まず、酸化ニオブ粉末と９９．９９％炭酸リチウム粉末とを１３６．６２６ｇ：３５．９１ｇの割合（モル比換算においてＬｉ２ＣＯ３：Ｎｂ２Ｏ５が４８．６０：５１．４０）で混合し、得られた混合物を白金ルツボに入れて高周波加熱により溶解する。そして、得られた溶融液を用いて、チョクラルスキー法（単結晶の育成速度（引き上げ速度）が０．５ｍｍ／ｈ、回転速度が３０ｒｐｍ）によってニオブ酸リチウム単結晶を製造する。このようにして製造された単結晶の外観検査を行って評価を行った。評価の結果、全く「ねじれ」がなかった場合は「◎」と、極わずかな「ねじれ」があった場合は「○」と、わずかに「ねじれ」があった場合は「△」と、はっきりと「ねじれ」ていた場合は「×」と評価した。
Lithium niobate single crystal production test Further, lithium niobate single crystals (LN single crystals) were produced using the niobium oxide powders obtained in Examples 1, 4, 18, and 23-25. First, niobium oxide powder and 99.99% lithium carbonate powder were mixed at a ratio of 136.626 g: 35.91 g (Li 2 CO 3 : Nb 2 O 5 was 48.60: 51.40 in terms of molar ratio). The obtained mixture is put into a platinum crucible and dissolved by high frequency heating. Then, using the obtained melt, a lithium niobate single crystal is produced by the Czochralski method (single crystal growth rate (pulling speed) is 0.5 mm / h, rotation speed is 30 rpm). The appearance of the single crystal thus produced was evaluated and evaluated. As a result of the evaluation, if there is no “twist” at all, “◎” indicates that there is a slight “twist”, and “△” indicates that there is a slight “twist”. And “twisted” were evaluated as “x”.
表４に示されるように、比較例１，２の酸化ニオブ粉末は均一混合性および流動性に劣っていた。これに対し、各実施例の酸化ニオブ粉末は、均一混合性および流動性に優れていた。この結果、ピークｐ（２θ＝２２．６°±０．５°の位置または２θ＝２８．４°±０．４°の位置に出現したピークのうち最も強いピーク）の半値幅（２θ）が０．０８°〜０．８°である酸化ニオブ粉末が好ましいことが解った。そして、均一混合性により優れるという点で上記半値幅が０．１°〜０．５°であるものがより好ましく、さらに、流動性に優れるという点で上記半値幅が０．１５°〜０．４°であるものがさらに好ましいことが解った。 As shown in Table 4, the niobium oxide powders of Comparative Examples 1 and 2 were inferior in uniform mixing and fluidity. On the other hand, the niobium oxide powder of each example was excellent in uniform mixing property and fluidity. As a result, the half-value width (2θ) of the peak p (the strongest peak among the peaks appearing at the position of 2θ = 22.6 ° ± 0.5 ° or 2θ = 28.4 ° ± 0.4 °) is obtained. It has been found that niobium oxide powder having a temperature of 0.08 ° to 0.8 ° is preferable. And the thing whose said half value width is 0.1 to 0.5 degree is more preferable at the point that it is excellent by uniform mixing property, and also the said half value width is 0.15 degree-0.00 from the point that it is excellent in fluidity | liquidity. It has been found that the angle of 4 ° is more preferable.
表５に示されるように、各実施例の酸化ニオブ粉末は、均一混合性および流動性に優れていた。そして、各実施例のピーク強度に着目すると、実施例４，１０〜１４ではピークｑよりピークｐの方が強度が強かった（Ｐ＞Ｑ）が、実施例１５〜１９ではピークｑの方が強かった（Ｐ＜Ｑ）。この結果、ろ過（工程１３）後に得られた沈澱物（焙焼対象物）中のフッ素含有量が一定であっても、焙焼工程のうち、第２段階の焙焼における焙焼温度が高くなると、ピークｑのピーク強度Ｑの方が強くなることが解った。なお、ピークｐの方が強かった実施例４，１０〜１４についてピークｐの半値幅を見てみると、０．２２°〜０．５６°であり、いずれの実施例とも先に説明した好適範囲内（０．０８°〜０．８°）の値であった。また、均一混合性に優れる実施例に限った場合、半値幅の範囲は０．２２°〜０．４２°（０．１°〜０．５°の範囲内）となり、さらに流動性に優れる実施例に限った場合、半値幅の範囲は０．２２°〜０．３５°（０．１５°〜０．４°の範囲内）であった。他方、ピークｑの方が強かった実施例１５〜１９についてピークｑの半値幅を見てみると、０．１２°〜０．２８°（０．１°〜０．５°の範囲内）であり、いずれの実施例とも先に説明した好適範囲内の値であった。また、均一混合性および流動性に優れる実施例に限った場合、半値幅の範囲は０．１６°〜０．２８°（０．１５°〜０．４°の範囲内）であった。この結果、先に説明した最大ピークの半値幅の好適範囲は、２０°〜３０°の間の最大ピークがピークｐである場合に限らず、ピークｑである場合にも適用できる範囲であることが解った。 As shown in Table 5, the niobium oxide powder of each example was excellent in uniform mixing property and fluidity. Focusing on the peak intensity of each example, the intensity of peak p was higher than that of peak q in Examples 4 to 10-14 (P> Q), whereas in Examples 15 to 19, peak q was better. It was strong (P <Q). As a result, even if the fluorine content in the precipitate (roasting object) obtained after filtration (step 13) is constant, the roasting temperature in the second stage roasting is high in the roasting step. Then, it was found that the peak intensity Q of the peak q is stronger. In addition, when looking at the half-value width of the peak p in Examples 4 and 10 to 14 where the peak p was stronger, it was 0.22 ° to 0.56 °. The value was within the range (0.08 ° to 0.8 °). Moreover, when it restricts to the Example which is excellent in uniform mixing property, the range of a half value width will be 0.22 degree-0.42 degree (within the range of 0.1 degree-0.5 degree), and implementation which is further excellent in fluidity | liquidity. When limited to examples, the range of the full width at half maximum was 0.22 ° to 0.35 ° (within a range of 0.15 ° to 0.4 °). On the other hand, looking at the full width at half maximum of the peak q for Examples 15 to 19 where the peak q was stronger, it was 0.12 ° to 0.28 ° (within a range of 0.1 ° to 0.5 °). In all examples, the values were within the preferred range described above. Moreover, when it restricted to the Example excellent in uniform mixing property and fluidity | liquidity, the range of the half value width was 0.16 degree-0.28 degree (within the range of 0.15 degree-0.4 degree). As a result, the preferable range of the half-width of the maximum peak described above is not limited to the case where the maximum peak between 20 ° and 30 ° is the peak p, but is also a range that can be applied to the case of the peak q. I understand.
そして、均一混合性および流動性に着目すると、比較例３，４の酸化ニオブ粉末は劣っていたが、各実施例の酸化ニオブ粉末は優れていた。この結果、第２段階の焙焼における焙焼温度は、５００℃〜１２００℃が好ましいことが解った。 When attention was paid to uniform mixing and fluidity, the niobium oxide powders of Comparative Examples 3 and 4 were inferior, but the niobium oxide powders of the respective examples were excellent. As a result, it was found that the roasting temperature in the second stage of roasting is preferably 500 ° C to 1200 ° C.
表６に示されるように、第２段階目の焙焼の焙焼条件が一定であっても、ろ過（工程１３）後に得られた沈澱物（焙焼対象物）中のフッ素含有量によって、最大ピークがピークｐになる場合と、ピークｑになる場合とがあった。具体的には、フッ素含有量が比較的多くなるほど、ピークｑが最大ピークになる傾向があり、上記実施例２０〜２７ではフッ素含有量が０．８質量％を超えると、ピークｑが最大ピークとなった。また、実施例２３〜３０では、いずれの実施例においても最大ピークの半値幅（２θ）は０．１°〜０．５°という好適範囲内であり、均一混合性および流動性について良好な結果が得られた。ただし、実施例２５，２６の酸化ニオブ粉末は、実施例２４，２７のものと比べると、実用上問題ないレベルであるが、流動性が若干悪かった。このような結果から、ピーク強度比（Ｑ／Ｐ）が０．５〜２の範囲である酸化タンタル粉末は、流動性が若干悪くなることが解った。 As shown in Table 6, even if the roasting conditions of the second stage roasting are constant, depending on the fluorine content in the precipitate (roasting object) obtained after filtration (step 13), There was a case where the maximum peak was the peak p and a case where it was the peak q. Specifically, the peak q tends to become the maximum peak as the fluorine content becomes relatively large. In Examples 20 to 27, when the fluorine content exceeds 0.8% by mass, the peak q is the maximum peak. It became. Further, in Examples 23 to 30, the full width at half maximum (2θ) of each example is within a preferable range of 0.1 ° to 0.5 °, and good results for uniform mixing and fluidity are obtained. was gotten. However, the niobium oxide powders of Examples 25 and 26 were at levels that were practically no problem as compared with those of Examples 24 and 27, but the flowability was slightly worse. From these results, it was found that the tantalum oxide powder having a peak intensity ratio (Q / P) in the range of 0.5 to 2 has a slightly poor fluidity.
表７に示されるように、比較例５，６の酸化ニオブ粉末は均一混合性および流動性に劣っていたが、実施例２８の酸化ニオブ粉末は均一混合性および流動性に優れていた。この結果、第１段階の焙焼における焙焼時間は２時間以上が好ましいことが解った。また、比較例７，８の酸化ニオブ粉末は均一混合性および流動性に劣っていたが、実施例２９，３０の酸化ニオブ粉末は均一混合性および流動性に優れていた。この結果、第１段階の焙焼における焙焼温度は、３００℃〜４００℃が好ましいことが解った。 As shown in Table 7, the niobium oxide powders of Comparative Examples 5 and 6 were inferior in uniform mixing and fluidity, but the niobium oxide powder in Example 28 was excellent in uniform mixing and fluidity. As a result, it was found that the roasting time in the first stage roasting is preferably 2 hours or more. Further, the niobium oxide powders of Comparative Examples 7 and 8 were inferior in uniform mixing property and fluidity, whereas the niobium oxide powders of Examples 29 and 30 were excellent in uniform mixing property and fluidity. As a result, it was found that the roasting temperature in the first stage roasting is preferably 300 ° C to 400 ° C.
表８に示されるように、ニオブ酸リチウム単結晶製造試験の結果、実施例４ではねじれは見られなかったが、実施例３１では極僅かなねじれが見られ、実施例３２は、僅かなねじれが見られ、実施例３３では、ねじれが見られた。この結果、ニオブ酸リチウム単結晶の原料としては、モリブデン含有量が２０質量ｐｐｍ以下の酸化ニオブ粉末が好ましく、１０質量ｐｐｍ以下のものがより好ましく、１質量ｐｐｍ以下がさらに好ましいことが解った。 As shown in Table 8, as a result of the lithium niobate single crystal production test, no twist was found in Example 4, but a slight twist was found in Example 31, and a slight twist was found in Example 32. In Example 33, twisting was observed. As a result, it was found that the niobium oxide single crystal raw material is preferably niobium oxide powder having a molybdenum content of 20 mass ppm or less, more preferably 10 mass ppm or less, and even more preferably 1 mass ppm or less.
本発明に係る酸化ニオブ粉末は、流動性および均一混合性に優れるものであり、ガラス（特に光学ガラス）、セラミック、薄膜形成材料、さらにはニオブ酸リチウム単結晶の原料として好適である。 The niobium oxide powder according to the present invention is excellent in fluidity and uniform mixing properties, and is suitable as a raw material for glass (particularly optical glass), ceramics, thin film forming materials, and lithium niobate single crystals.
Claims (3)
２θ（回折角）＝２０°〜３０°の範囲の最大ピークが２θ＝２３．２°〜２６．２°の範囲に出現し、
フッ素含有率が３０００質量ｐｐｍ以下であり、
モリブデン含有率が２０質量ｐｐｍ以下である酸化ニオブ粉末。 The maximum peak in the range of 2θ (diffraction angle) = 20 ° to 30 ° in X-ray diffraction analysis using CuKα 1 line has a half width of 0.08 ° to 0.8 °,
The maximum peak in the range of 2θ (diffraction angle) = 20 ° to 30 ° appears in the range of 2θ = 23.2 ° to 26.2 °,
The fluorine content is 3000 mass ppm or less,
Niobium oxide powder having a molybdenum content of 20 mass ppm or less.
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